Thursday, 30 December 2010

Free flow

You've trained for this sort of thing, sure... in that warm swimming pool, kneeling around the instructor, the surface an undulating mirror a few feet above your head.  Hold the button down on your regs, pretend its jammed, and as the air flows around you, take breaths from one side and let the excess stream past. Don't panic, you can still get air... just head to the surface and swim back to the boat. Just one more safety lesson they will teach you, one more you'll soon forget as you swim through multi-hued reefs and watch the myriad displays of sea life dance around you. Besides, you'll hear frequently that most regulator free flows take place on the surface, at sub-zero temperatures, not underwater in warm tropical seas.

And who in their right mind would be diving in sub-zero weather?

Our goal was simple... drop down to the bottom , take a bearing at the sunken airplane, then head off at 145 degrees until we reached the gnome garden.  My buddy would navigate, I would be running the camera - not at anything special, but I wanted to try capturing a continuous film of a dive, rather than my usual 30 second clips of an interesting fish or curious lobster.  The quarry with its limited distractions seemed as good a place as any to try and I had never been to the gnome garden before... and the cold weather?  Well, it promised a swim free of other divers, and hopefully a bit less of the algae that clouded the waters each summer.

Ten minutes in, and we have problems.  Free flows may be more common at the surface, but in water only a few degrees above freezing they can happen at any depth. At that moment we were 15 meters below the surface and my buddy was engulfed in a column of bubbles as his regs vented precious air.  This shouldn't be a problem... we are trained what to do, after all, but quarry diving in winter adds a few extra dimensions not covered in the training courses I took years ago. The first problem is the venting regulator - not only is it depleting my buddies air, but the bubbles are blocking his vision and threatening to knock free his mask - the last thing he needs is the shock of ice-cold water hitting his face if his mask comes free.  Taking off your mask in warm water is an unpleasant enough experience - when the water is three degrees I would challenge anyone not to panic.  This time, at least, luck is on our side, and he could switch to the spare reg on his pony bottle (a christmas gift - who would have thought he would need it so soon?) but with air going fast we needed to get to the surface.

The second problem of diving in cold water is that to even be in the water safely you need a dry suit. A dry suit is basically a bag of air that surrounds you, and much of the art of dry suit diving is learning to manage that bag of air so that you don't go shooting to the surface like a balloon.  This is accomplished by carrying large amounts of lead (15 kilos, in my case) to counteract both natural boyancy and the boyancy of the air in the dry suit.  Without a bit of air in the dry suit, one has a tendancy to go to the bottom.  Even with a secondary air supply, my buddy still needed air to control his ascent and to stay on the surface.  With thick gloves and frigid hands, creative solutions such as shutting off his main tank until we surfaced were out of the question.

Surfacing in murky water is harder than it sounds... you have no reference points, no sight of ground below or the surface above, only your depth gauge or dive computer to tell you where you are.  You don't want to go straight up - that risks the bends - but with a limited air supply,  patience isn't a virtue.  I think we spent the first 30 seconds finning away before we realized we weren't going anywhere - just bobbing back and forth a few meters above the ground.  Guided by the depth display on our computers, we slowly made our ascent to six meters, before my buddy signalled for us to halt our ascent, giving me the sign for a three minute decompression stop.  I was a bit surprised - ten minutes at 15 meters isn't long enough to need a safety stop - and the gauge for his tank was still dropping.  The back-up air supply had given him a bit of confidence - but maybe a bit too much - it couldn't inflate his boyancy jacket and with only a small air supply, he couldn't have had more than a few minutes left on his reserve.  Still... what could I do?  So there we were, hanging about at 6 meters, a stream of bubbles pouring from the regulator dangling at his side, while his gauge dropped into the red and I wondered when his pony tank would run out.  A minute and a half in, and I finally decide enough is enough - the surface was in sight, but any longer dallying about and he would never reach it. An executive descision had to be made.  Grabbing his jacket, I signalled upwards and began my final ascent, lifting him with me.  Only at the surface, his jacket now inflated with the last wisps of his air, could I finally relax. 

The long wait at 6 meters seemed to me a bit silly, given the circumstances, but it could have been different.  If we had been down longer, or deeper, a straight run to the surface could have had much more dire consequences... there is a reason that novice divers are told not to go below 18 meters, where optional stops become mandatory and the surface may as well be a hundred meters away for all that you can safely flee to it.

And as for my attempt at filming?  Turns out my camera has difficulties at cold temperatures.

I guess for now, its another 30 second short feature.

Monday, 6 December 2010

Rat whispering

He doesn't have a name yet.  If he had a name before, I'll never know.  He was found a week ago trapped in a cage someone had left in a skip, just before the snows came.  I found him in the local animal shelter, and brought him home two days ago. 

I've kept rats most of my adult life... 28 now, over a 16 year period, but he is clearly the most timid one I've come across.  He doesn't like being picked up, and bolts for the small plastic 'house' in the corner of his cage when I try... I've been bitten once already, for foolishly trying to block his escape with my hand, the first time a rat has bit me in all these years.  Pet rats aren't normally that frightened, which makes me wonder if he suffered more than just neglect before we took him in.  But with treats and quick handling I can get him out of his cage, and while still timid, the generous helpings of food I've been rewarding him with seem to be having a positive effect on his behavior.  At the very least, he hasn't bit me yet today.

The next step is training him to trust me... applying a rat version of the Rarey technique to convince him that I'm not a threat.  That means more treats, lots of positive reinforcement, and lots of interaction.   At the end of it all, I may have a fat rat, but at least I'll also have all my fingers.

Tuesday, 30 November 2010

Real life catches up

I've been away for a while, but will be posting soon with more of my underwater (and above water) adventures...

In the mean time, it would be nice to know if anyone comes by and reads this blog. Do I have any regular readers, or just people drifting through?

Thursday, 14 October 2010

Crab porn

Two mating velvet crabs, not particularly happy to be interrupted. The male (the larger one) is 'mate guarding' the female... basically standing over her to protect her (mating takes place after the female moults, when her exoskeleton is still soft and she is vulnerable to predators) and to ensure no other male gets any ideas.

The video was taken at a depth of about 15 to 18 meters at St. Abbs, Scotland.

Wots that fish?

It happens to everyone... your cruising along at 18 meters through the pea soup that passes for ocean water in the North Atlantic when suddenly you spot a few colorful fish in your beam, darting in and out of the sea weed...

... or maybe its just a single fish, examining you from the security of a rock cleft....

... or possibly its a discoloration of the sand, that swims away as you pass over (after a bit of prodding with your torch, anyway)

You reach for your handy guide to the fish of the northern Atlantic waters (in my case a 40 year old copy of Collins Guide to Sea Fishes) and ignoring the difficult interactions of paper with water at depth, you flip to the appropriate page and quickly realize that you are seeing....

... well, no, actually, its not that clear... The difficulty of many of these fish guides is that they make a few assumptions about your situation, namely that you are viewing the fish from the side, in good light, on the surface, while the fish in question sits perfectly still with its fins outstretched. The pictures in the guides vary from  black and white sketches (not good if the obvious difference between species is color pattern), paintings (often taken from dead and slightly faded fish) or pictures of pickled specimens. It gets worse if you go to the technical literature... Handbook of the Marine Fauna of North-West Europe is one of the best books for identifying UK sea life, but unless you regularly take a dissecting microscope and a jug of formaldehyde on your dive trips its not going to be much use (who can count fin rays at depth, anyway?)  I have a personal rule about collecting live specimens (that is, I won't) so I'm limited to either a photograph or a short movie clip taken under what I would politely call less than ideal conditions.

 Fortunately, there seems to be more sea life publications written by divers for divers in recent years, with photos taken from life rather than illustrations or images of dead specimens. Without such aids, I would have been hard-pressed to identify either of these fish, as they belong to the Gobies, one of the more difficult fish groups.

  The species, incidentally, are female Two-Spotted Gobies and a lone Common Goby.

Tuesday, 28 September 2010

Pea crabs

I had a bit of a surprise in my dinner over the weekend... after boiling up a bag of mussels, I found several odd-shaped crabs at the bottom of the water. Pea crabs, as it turns out... a not exactly uncommon but rarely seen member of Englands aquatic community.

Pea crabs and their relatives (Family Pinnotheridae) are best known as parasites of clams and mussels, although they have also been found affecting sea urchins, sea cucumbers, and tube worms. Most of what is known about these crabs comes from a few species that infest edible mussels and oysters, and because of this, the literature on the life history of pea crabs can be confusing and contradictory. The adult female pea crab is the best studied life stage, for the obvious reason that this is the stage most frequently encountered. Much less is known about the males and the early free-living stages, and what is known comes from captive animals observed in aquaria.

The general opinion is that pea crabs pass through several planktonic stages before moulting into a recognizable crab shape, although some species of pea crabs may hatch skip the planktonic stage. The young crab stage is characterized by a hard shell and flattened hairy legs for swimming. In this stage, both males and females have a free-living existance while looking for suitable hosts. Following entry into a host mussel, the female undergoes a transition (over several molts) into the familiar pea-shaped crab with a soft shell and limited mobility. Following these molts the female grows too large to leave its host, and its legs become smaller and weaker, sufficient to move around inside the mussel but not to live outside.

The male will continue to grow through several more molts, but is less dependant on a host mussel. In the British Pea Crab, the males remain small and can alternate between a soft-shelled form adapted to the inside of a host and a free-living hard-shelled form adapted for moving between hosts, with the season guiding their decision on whether to be soft-shelled or hard-shelled at any given time. Its less clear whether males of other pea crabs can switch between hard and soft shelled forms, however. The hard exoskeleton helps protect the crab both in the outside world and during the dangerous process of entering a mussel - the mussel can close down on a crab, potentially crushing it or snipping off legs, and males missing a leg or two show up with regularity inside mussels.

Female pea crabs are obligatory parasites once they settle in a host. The female doesn't actually feed on its host, however, rather it steals food from its host - though this has the effect of damaging the gills, causing local irritation of the mantle lining and reducing the growth rate of the host. The male can presumably also steal food from its host, but its less clear how dependent it is on the host mussel in the wild, and it may prove to have a largely free-living existance. The male sports fringes of hairs on its (flattened) legs which enable it to swim and hard shelled forms are restless, frequently leaving and re-entering hosts when in captivity. As all of the behavioral studies are based on captive individuals kept in aquaria with lots of mussels (and probably not much else), its not clear how much of their time hard-shelled males actually spend in hosts - it is probable that they are only part-time parasites.

Wednesday, 22 September 2010


The spanish have a reputation for being friendly, and that seems to extend to their shrimp....  these small shrimp on Tabarca Island are happy to be hand-fed pieces of bread.

Of course, not all were so friendly... this one tried to 'attack' the camera.

Sunday, 19 September 2010

A well stocked table

The mediterranean isn't known for its diversity of life... you won't find the vast array of colorful fish that inhabit the reefs of the Red Sea, nor will you see the complex habitats of the North Atlantic kelp forests.  Much of the inshore western mediterranean is composed of vast lawns of sea grass interspersed with rocks and the occasional wreck, and supports a limited range of sea life.  The med has undergone several cycles of drying out, and the sea life within it represent the descendents of a relatively recent recolonization over the last 5 million years.

One advantage of this reduced diversity is that when you are in the med, rather than being distracted by a variety of fish, you can pay more attention to what they are actually doing.  One interesting behavior I noted was of clusters of seabream and wrasse feeding on the rocks... the smaller Rainbow Wrasse and Ornate Wrasse would hover around the larger seabream  and Ocellated Wrasse, letting them do the heavy lifting of tearing chunks of algae and encrustations off the rocks, before diving at the debris cloud to grab any interesting food morsels that were shaken free.

You can see some of this behavior in the first half of the clip below, where off to the right several small wrasse are diving through one such cloud of debris, from where a seabream has pulled away some of the encrustations.  Near the end of the clip is a different behavior - a watchful Painted Comber assessing my intentions before deciding that discretion is the better part of valour and fleeing into a nearby cranny.

For those interested in which fish is which, the two larger fish in the above photos are the White Seabream (oval with one tail spot) and Two-Banded Seabream (oval with two stripes), while the Ocellated Wrasse is the large wrasse with a small spot near the tail. There are two species of smaller wrasse in the photos and movies - the wrasse with a red stripe interrupted by a black bar is a male Mediterranean Rainbow Wrasse, while the female of the species has the dark upper body and light colored underside.  The orange wrasse with the light bands and black spot near its back is an Ornate Wrasse.

Thursday, 16 September 2010


Every dive is an adventure, and for a (former) biologist like myself, the sea is a wealth of interesting and unusual creatures, behaviors, and relationships.

While snorkeling near Tabarca Island in the med, I came across a mauve stinger jellyfish (Pelagia noctiluca) that was swimming in close association with a tiny fish.  If you watch through the movie clip (its a bit jerky, as I was both trying to keep the camera on the jellyfish and avoid getting too close) you'll see the little fish swimming around the bell of the jellyfish.

If you are having trouble seeing him (he was very quick) you can spot him in this still from the video, just to the left of the jellyfish. Throughout the whole encounter, he never strayed more than an inch or two from the bell of the jellyfish.

Notice something else about the jellyfish? Its missing its tentacles! (Compare with the picture on the wikipedia page). This starts to give a clue as to the relationship between these animals.

It took a bit of digging to find anything on these relationships, but I came across an old paper talking about similar symbiosis between young fish and an atlantic jellyfish species (Copeia, Vol. 1963, No. 1 (Mar. 30, 1963), pp. 40-80).  The paper describes how larval fish associate with jellyfish Chrysaora quinquecirrha when they are young, using the jellyfish first as protection, then as a ready food supply, nibbling pieces of their host until they are large enough to eat them entirely and live an independent life.  That paper also mentions an even earlier 1915 paper that describes how young scad seek shelter among jellyfish, using them initially for protection before consuming their gonads and tenticles as they get older.  The unwillingness of the larval fish to leave the proximity of the jellyfish and the lack of tentacles on its host suggest that what I filmed is one of these symbiotic relationships, and that it won't be much longer before this larval fish is ready to leave its host for an independent life.  

I would be curious if anyone else has filmed this relationship between a fish and a mauve stinger... there doesn't appear to be much in the scientific literature and given the age of the papers I found, I doubt anyone in the 60's (never mind 1915) was plunking a camera into the mediterranean to chase jellyfish.  So I guess what you are seeing here is a scientific first...  in my museum of curiosities.

Wednesday, 15 September 2010


I have to wonder what was going through the mind of this saddled seabream as I came up behind it.

These fish were surprisingly calm around divers, though if you got too close they would move away.  I suppose there hasn't been much natural selection favouring a flight response from large, ungainly sea creatures streaming bubbles and making regular rasping noises, but more likely it just isn't worth the effort to flee from every large creature in the ocean... a truly timid pelagic fish would be a very exhausted fish and not one to contribute to the next generation.

A side view of one of these fish.  The latin name is Oblada melanura. (as an aside, I need to get some better identification guides for the mediterranean... I have one very old guide, and the pictures in it don't do the live fish justice.)

Sunday, 5 September 2010

Shore diving

Diving the british coast can be an amazing experience, with a diversity of life unlike anything you'll find in the tropics.  You just have to be willing to brave cold waters, bad weather, and a visibility measured in inches instead of meters.

This weekend I was at St. Mary's Lighthouse, north of Newcastle.  This is how the tourists see St. Mary's:

and this is how I saw it:

Probably due to the shallowness of the dive site and the proximity of a sandy beach, there was not as much life as at places farther north up the coast, but there were still crabs, lobsters, turban snails, and sea anemones.  The high point of the dive was finding a small blenny curled in an S shape, hoping not to be noticed, then darting off when it realized it had an audience!  The low point (or sad point, really) was coming across a large lobster trapped in an abandoned lobster pot... if I had thought to bring a dive knife I could have cut it free, but as it was, I had to leave it behind.  There something about seeing these large, beautiful crustaceans when they are alive and in their native habitat that makes it seem like such waste to trap and eat them.

The visibility in the water was too poor for most of my attempts at photography, but I did manage a short film clip of a crab scuttling away from us.  It also gives you a bit of an idea of the visibility I had to deal with.  Getting lost was a constant risk, even with a compass,  and we had to surface several times just to figure out where we were!

Wednesday, 1 September 2010

A good day for butterflies

A recurring theme of mine is how few insects there are in the UK, compared not only with areas of similar climate in North America, but also with the UK of 100 or even 50 years ago.  A quick glance at old identification guides or museum collections show just how much diversity has been lost, and how the numbers of many species have crashed.  No surprise given the changing land use in this country... hedgerows, for example, have been lost at an alarming rate, despite their role as wildlife refuges in the otherwise monoculture environments of England.

This weekend was one of those rare days when I've seen a lot of insect life.  The Yorkshire Dales are one place you would think would be a good place for seeing butterflies and moths, given the diversity of habitats and the smaller scale of farming, but years of bad weather have, I suspect, knocked down the numbers of leps in this region.  Yet this weekend, on a nice warm day near Hawes, I saw more butterflies (and more numbers of butterflies) than at any other time in the years I've lived here.

On top of the more common Small White and Green-veined White, there were the less-seen Large Whites, Small Tortoiseshells, Peacock butterflies and even a Red Admiral, but the prize for the day was seeing a Fritillary, a rare sight at the best of times.  Unfortunately, I was too slow with my camera (and the butterfly itself was in no great shape) so I don't know what type it was, but if I had to guess I would say it was a Silver Washed Fritillary.  Hopefully when I can look up some range information I'll have a better idea.

Some of the butterflies I saw:

Small Tortoiseshell

Large White


Red Admiral

Thursday, 26 August 2010

Flatworms again

I checked on the flatworms a few days ago and found that:

1) I had a few less flatworms than I did before (specifically, the Dendrocoelum lacteum were missing)
2) I had 5 small brown balls attached to the upper sides of the tank, near but below the water line.

My first thought is that the Dendrocoelum had encysted somehow, as perhaps my tank was not to their liking, but after delving into the subject, I'm afraid it looks like Dendrocoelum has become the perfect meal for my Dugesia, supporting a round of egg-laying by that species.  The eggs themselves are inside the cocoons, but i expect in a few weeks I'll have numerous baby Dugesia circling my tank.

Saturday, 21 August 2010

It came from the compost heap!

One of the more familiar sights of summer is the hoverfly, that yellow bee-like insect that darts from flower to flower, or hovers in mid-air, surveying its surroundings.

But how many people have ever seen their larva?

Below is a rat-tailed maggot... larva of one of the larger groups of hoverflies, the Eristalinae.  This fellow had established himself in our compost bin and was quite happy to turn our waste veggies into hoverfly material until I tipped him onto the compost heap out back.

That long bit sticking out the back (the 'rat tail') is a breathing tube allowing the maggot to live in waterlogged sewage, in temporary ponds, or in any environment with lots of water and lots of organic material.  I'm guessing this is a sign I need to empty the compost more frequently, though on the flip side, I can think of no better fly to be chowing down on our leftovers.

Incidentally, the fly pictured at top, Episyrphus balteatus, doesn't produce rat-tailed maggots...  its larva are one of the few active, predatory fly larva and look something like small green slugs.  They feed on aphids and can be found, with some careful searching, on garden plants that have been aphid infested.

Friday, 13 August 2010

Flatworm pictures

Some pictures of the flatworms.  The animals were transferred to a small plastic container and photos were taken with a macro lens.  It was a bit harder than I thought it would be to get decent pics, but these are probably the best I could hope for with the equipment I have.

Incidentally, its not really clear what I should feed them.  In some of the old literature with Dugesia tigrina, the authors use small cubes of liver.  In the 60's, that probably wasn't hard to find, but few supermarkets stock liver these days.  Liverwurst is not a substitute, apparently, but I will try some chicken meat soon.  I've also tried dried bloodworms, which some of them have gone for, but its not entirely clear if they are feeding or just clinging on to them.  The problem is that these are predators (Dendrocoelum in particular) and only occasionally scavengers, so I imagine simply wiggling a dead bloodworm in front of them isn't going to provoke much of a response.

Dugesia lugubris

Dendrocoelum lacteum

(Note the eyes - Dugesia has large eyes that look 'cross-eyed' - the white bit is many retinal cells, the dark patch a few pigment cells. Dendrocoelum has just two dark dots composed of two retinal cells and a pigment cell.)

Thursday, 12 August 2010

Flatworms III

Some pictures of my flatworms: Dendrocoelum lacteum (left) and Dugesia lugubris (right). If the picture looks a bit odd, its because it was taken through the plastic of the tank with a macro lens, and what your seeing is the undersides. The lighter patch in the middle of each worm is the pharynx, which is popped out when the animal wants to suck up some food. Flatworms don't have a through digestive system, so its also where the waste leaves when digesting is done.

Despite their similarity, these species are not close relatives. Dendrocoelum is in the family Dendrocoelidae, a group of active hunters with very simple eyes and an 'adhesive organ' (sucker) at the front for holding their prey, while Dugesia is in the family Dugesiidae, a more opportunistic predator that lacks a sucker but has a much more complex eye. These species used to be all lumped together in a larger group, the Paludicola, defined as all triclad planarians (triclads are flatworms whose intestine divides into three parts) that live in fresh water. They were believed to have descended from terrestrial flatworms, who were themselves descendents of marine flatworms.

About 10 years ago, a series of molecular studies completely rewrote the book on flatworm taxonomy and gave us a very different view of their evolution. The freshwater triclad flatworms are now believed to have evolved from marine flatworms (which when you think about it, makes more sense than if they had come from terrestrial species), and at some point around 100 million years ago, the ancestor of the Dugesiids and all terrestrial flatworms split off from the ancestor of Dendrocoelum. In the process they gained a rather unique mutation - a second version of their ribosomal RNA genes. All animals have multiple copies of their ribosomal RNA genes, but because all these copies are next to each other on the DNA strand, the mechanisms of DNA copying ensure that they are all identical copies. At some point, the ancestor to the Dugesiids and land flatworms underwent a mutation that moved some copies of their ribosomal RNA genes to a different location in their chromosomes, where they could evolve in a different direction. Its not really clear what these second ribosomal RNA genes do, but they are expressed and they can be found in all of the descendents, so they must be doing something important, but different from the original ribosomal RNA. My guess is that they may only be expressed in certain tissues or at certain times of development, but I don’t think anyone has really looked into it.

Flatworms II

Part of my fascination with these humble flatworms comes from their ability to regenerate - as a youth, I remember coming across drawings of two-headed flatworms, multiheaded flatworms, and full-sized flatworms with a 'miniature' flatworm emerging from their sides. Not all flatworms display this amazing ability to regenerate, of course - depending on which version of flatworm taxonomy you accept, regeneration is thought to be an ancestral characteristic that has been reduced or lost multiple times in the evolution of this group. Some flatworms can't regenerate at all, others can regenerate most of their body, as long as the brain is intact, but for most flatworms regeneration of amputated parts tends to be limited to an area from their brain to their mouth (located around the middle of their body). They do a bit better at regenerating cuts, which leads to two-headed flatworms if you make a cut along their midline.

The flatworms that do regenerate have a cells scattered through their body called neoblasts that are thought to be totipotent - the flatworm equivalent of stem cells. When a flatworm is damaged, these cells migrate to the wound site and begin dividing and differentiating to make new tissues. What is interesting about this process is why not all flatworms regenerate, and why some are not as good at it as others even though they have neoblast cells... if you think about it, these cells are a two-edged sword. On the one hand, they allow the animal to quickly repair damage and replace lost body parts (and considering how soft and delicate these animal are, I'm sure damage is quite common), on the other hand, these cells have to be kept under tight regulation or they run the risk of replicating out of control - essentially becoming cancer cells. Even a regeneration that is 'mostly' correct can be fatal - two headed flatworms appear to die after a month or so. I suspect that for some lineages of flatworms, the risks of uncontrolled regeneration or cancer have outweighed the benefits of fast healing and replacing amputated parts, and over time the ability to regenerate has either been lost outright or various mechanisms to regulate and restrict these cells have evolved.

Of course there are other factors that may help maintain the ability to regenerate. A number of flatworm species can reproduce by splitting in two, and while there are differences between fission and regeneration, neoblast cells are involved in both processes. Interestingly, in some of these asexual species, if they do become sexual and develop ovaries, they lose much of their ability to regenerate. There are also similarities between early growth and regeneration, suggesting that regeneration could be a retention in the adults of growth mechanisms in the juvenile. It would be interesting to look at some of the poor- and non-regenerating species and see if their juveniles show greater regenerative powers than the adults.

As for my own flatworms, I'm a bit undecided as to whether I will be cutting them up to create two-headed monsters of the water-tank... for one, cutting a tiny flatworm is probably a lot harder than it sounds if all you have is an old microscope, a hand-lamp, and a kitchen knife (ah for the days when I had access to a full laboratory!). For another, where people have bothered to study the fate of these multi-headed worms, their lifespans have been much shorter than normal, and for now I just want to see if I can keep them alive in a small tank. These aren't the 'classic' lab flatworms with the arrow-shaped heads (Dugesia tigrina), so I don't have as much to go on about culturing these species.

Tuesday, 10 August 2010


Been catching flatworms in the river near where I live... I was able to catch several black ones, two grey ones, and a white one.  The black ones are almost certainly Dugesia polychroa... the white one possibly Phagocota vitta.  I'll have to wait a bit until they settle down before I can take a closer look at the white and grey ones.  Flatworms have always fascinated me, ever since reading about them in an old copy of 'Animals without backbones'.  The problem of course was finding them... the streams near where I lived (as a child) were muddy and not really suitable for them.  My identifications are from Ball and Reynoldson's "British Planarians", which may be a bit dated.  Hopefully I'll figure out a way to get some pictures of them posted.

Sunday, 1 August 2010

Beautiful blue

This blue jellyfish was kind enough to do a somersault, giving me a good view of both its top and underside.

My god, its full of stars!

Asterias rubens to be exact. These starfish were numerous at the dive site, mostly on rocks but some were on the shell-gravel. If you look carefully at both photos, you can see a second smaller starfish nearby in each of them.

This individual below is eating a clam - the clam isn't obvious, but the body of the starfish is positioned over it, and the stomach has been inserted into the clam shell.

Diving at St.Abbs

Common sea urchins in abundance at St. Abbs, Scotland.

Below, you can see the tube feet wafting in the current.

Saturday, 24 July 2010

Butterfly week

Its butterfly week, apparently....  not that your likely to see many in this part of England.  Years of wet weather has given the native species a big hit lately, but the ultimate cause is changing land use patterns that have reduced the available habitat and eliminated many of the host plants our native butterflies use.  The problem, of course, is its a gradual process that has been going on for the last 30 years, so many people today don't really realize what they are missing.  Coming from North America, its painfully obvious how few insects remain in England, but even just picking up an old UK field guide or nature book published in the 50's or 60's and flipping through the pages reveals insect after insect that is either locally extinct or rarely seen.

Anyway, some photos of a species that is still common here: a larval Vapourer moth (Orgyia antiqua) munching on my roses.

Friday, 23 July 2010

Coraline Cruelty

I've been reading an interesting paper in bioessays which redescribes the symbiotic relationship between corals and their algae from one of mutalism to one of... well.... vampirism? Slavery? Rather than happy zooxanthellae producing sugars for their grateful host while basking in the protection of the coral polyps cnidocytes, the little algae are tricked into getting close to the coral, mercilessly engulfed by the gut cells, and then have to undergo a cruel process of selection, where over a period of days to years, they are tested, and most digested, with an unlucky few forced to live a life of indentured servitude, producing carbon for their coraline masters!

I'll never look at a coral the same way again.

Wednesday, 30 June 2010

Its been a while

Real life insists on intruding... though given the great weather at the moment, I can't help thinking there are better things to do than spend my life on a computer. 

I've been thinking recently about the lack of insects in this country (a topic I've touched on before) and will post a bit on this over the next few days.  For now, a picture of a bumblebee... one of the few species in this group that seem to be doing well.

Sunday, 23 May 2010

Day flying moths

Real life has been bogging things down for me this week, but after a beautiful day in Harrogate, I have some great shots of day flying moths - one fairly famous one, and one less seen but equally interesting.

The Cinnabar moth (Tyria jacobaeae) is most famous as the orange and black striped caterpillars often found on ragwort that supposedly inspired W.D. Hamilton to lay down the theory of kin selection (or at least, thats the popular anecdote).  The caterpillars are both highly visible, very social and toxic, and birds that try to feed on one soon learn to leave them alone - thus the caterpillar that is eaten spares his brothers and sisters on the same plant a similar fate.  Of course, warning coloration is a bit more widespread and rarely do birds try and eat the caterpillars - as well as there being a degree of kin selection, the caterpillars are taking advantage of the fact that many other distasteful insects share the same coloration.

Smaller and less noticed is the Fairy Longhorn moth (probably Adela reaumurella), a member of one of the more primitive branches of the lepidopteran family tree. I observed dozens of them flying around the sunlit leaves of a single tree in a patch of forest near Harrogate - fortunately they were not too bothered by my presence and I could take this photograph.

Sunday, 16 May 2010

Sleepy sunday

I took this photo in south Australia, in an area of parkland containing thinly distributed eucalyptus trees interspersed among low bushes and grassland, not far from the remnant Myrtle Beech forest where I photographed the cicada molt skin.  There were several koalas in the area (easy to spot - just look for clusters of tourists with their cameras out), almost all fast asleep save for one who was casually munching away at the eucalyptus leaves.  The popular image of koalas is that they live an idyllic life of ease, probably due to the long periods they spend sleeping (up to 20 hours a day).  In truth, eucalyptus is such a poor food resource that they need these long periods of rest to digest it - I guess the advantage is that they don't have much competition. 

A hundred thousand years ago, there would have been no koalas where I took this photo - the forest would have been a dense thicket of Myrtle Beech, tree ferns, cycads, and other jungle plants, with few if any eucalyptus for a koala to feed on.  Koalas came to this section of parkland in south Australia with the eucalyptus forest, and the forest came with the aboriginals.  The practice of burning to clear the land pushed back the Myrtle forests, while the eucalyptus thrived in the fire zone.  Eucalyptus is highly adapted to fire, being able to both survive and spread after fire sweeps through the forests, while taking advantage of the fire to eliminate competing plant species... and I suppose hungry koalas.

Saturday, 15 May 2010

In the garden

I've been reading the book Garden Natural History which has inspired the latest round of backyard photography. Its fascinating how much goes on in the garden that most people aren't aware of - all the more so given my habit for letting it run a bit wild.  Most of the activity is below the surface - mites, burrowing insects, worms, and other scavengers of the soil (and the creatures who prey on them) but there is a host of activity going on above the surface - aphids, parasitoid wasps, flies and butterflies, and of course the host of mosses, lichens, fungi and other less-visible plants that along with the grass and garden plants are the basis of this ecosystem.  Its unfortunate that I'm probably one of the few people who appreciate all the activity going on in the back-yard... most people in England seem to want that perfect lawn (in other words a grass monoculture trimmed to resemble a sheep-grazed field, without the benefit of sheep dung or the various plants that thrive in sheep fields) while others have taken to removing the grass entirely and replacing it with stones or tiles.  Its almost as though the urban biodiversity of this nation is at the mercy of home-owners with an obsessive-compulsive view about tidiness and order.

Cuckoo flower

Cuckoo flower (Cardamine pratensis) from the garden. 

Friday, 14 May 2010

Silent Night II

By coincidence I came across an advertisement for this new book out Silent Summer which goes into detail what I've been noticing in the past few years - how the various insect and other invertebrate species are dying out in this country.  Sixteen years ago I visited the UK as a budding young entomologist and returned home with several specimens of what were at the time unprotected species, but which are now on the endangered list, if not actually extinct in this country.  Sixteen years is not a long time... barely a generation... yet in this time 5 species of butterfly have gone extinct here, and the majority of the remaining species are endangered. 

I'll need to get myself a copy of that book... I don't think it will make happy reading.

Thursday, 13 May 2010

Silent Night

I miss cicadas. 

I don't think most people in this country realize how noisy the countryside should be, or would think something is wrong when walking through a silent field at night.  There is only one species of cicada in England and its restricted to the New Forest in the south.  There are several species of crickets and grasshoppers as well, but I have only rarely seen them (again in the south) and never heard one calling.  To someone who grew up in the colonies, its horribly unnatural to hear so little of the night chorus and highlights the degree to which this country has extirpated its local fauna.  One of the saddest aspects is that thanks to Victorian and Edwardian collectors and enthusiasts, there is no country with a better record of the species of insects and other invertebrates that live here, and yet this record makes it painfully clear just how much the native species  have been extinguished from this island with so many species either locally extinct, pushed into patches of marginal territory, or in the case of the once common freshwater pearl mussel (Margaritifera margaritifera) and several of the oak species, only ancient individuals remain with no young having been recruited for decades.  Changing climates (and a run of bad summers) is expected to put several of the rarer butterfly species here at risk of extinction from these islands, but as these species have become so restricted in their locations, I'm not sure anyone but a handful of experts will notice that they are gone.

...and that of course is the problem.  Its been a slow and gradual process of loss, such that the scale has not been apparent to the average resident.  Most Englanders my age think that what they run across (or more, what they don't run across) when out in the countryside is "normal".  Their parents may remember there being more butterflies or more of some flowers (perhaps they once saw a lady slipper orchid in the woods - now these flowers are so rare they need police protection) but its been such a gradual process that even they have largely accepted it.  Its only once you look back at the old records - descriptions of clouds of moths surrounding gas lamps, or boxes containing hundreds of faded moth specimens - that you appreciate the scale of the loss.

The picture, by the way, is a cicada molt skin photographed in a small Myrtle Beech forest in south Australia. I've still never had the luck to find one here in England.

Tuesday, 11 May 2010


Among the butterfly fish, wrasse, parrotfish, and other colorful denizens of the reef, its easy to overlook some of the less spectacular but no less interesting inhabitants.  This fellow is a blackspotted pufferfish (Arothron nigropunctatus) that meandered into view while snorkeling on the reef near Cairns. He doesn't seem particularly bothered by my presence... not surprising as he has few if any predators to worry about, save the occasional japanese chef.

Its not one of the species that can be served as fugu, but its no less dangerous, and being packed full of tetradoxins no doubt gives it a sense of confidence that other, similarly sized fish might lack.

Wednesday, 5 May 2010

Why I won't vote labour

After reading the reviews of the candidates at whoshouldshipleyvotefor and attending a hustings myself, I have to say that I was more impressed than I thought I would be with the Labour candidate Susan Hinchcliffe.  Part of me thinks that she could be a decent MP for Shipley, and probably is more representative of my opinion than her most serious rival Philip Davies. 

However... (and its a big however), I don't think in the end it matters much what she does or doesn't believe.  The Labour party that I am familiar with is an autocratic organization in which the unelected but monied few have far more say than the elected MPs, and where during the Labour administration a rot has been allowed to set in throughout all levels of government that has led to both MPs and senior civil servants being more interested in personal advancement than in serving the country.  I've seen it personally, internally during a brief stint in government, and externally in the steady parade of external consultants and PFI businessmen (and women) who have infiltrated every aspect of government, taking huge amounts of taxpayer money and delivering nothing but promises.

And of course, theres the war.  I'm not sure if it would have made much of a difference to Bush if Blair had not gone along, but it certainly would have helped if Blair and the Labour party had not turned into lapdogs for an aggressive and misguided administration.  Theres is blood on their hands, and it is smeared over all of those who continue in Labours name.

Some things cannot be forgiven.


A fine specimen of Platax orbicularis, the orbicular batfish, observed underneath the boat off the barrier reef. These fish like to hang around near the boats during the day, to be replaced by sharks and trevallies during the night. 

Tuesday, 4 May 2010


Its unfortunate, but I seem to live in one of those ridings where the electorate is either red or blue, with no room for other voices.  How else to explain why the Lib Dems, who seem so energetic in other places, have such a lacklustre campaign here?  Its one of the unfortunate effects of the first-past-the-post system that voters in non-marginal constituencies are essentially ignored. 

I sent an email around to the various local candidates to see what their opinions were on the cut in university funding.  No response from the Lib Dem candidate, and the Green party candidate wanted to confirm that I lived in the riding (and why would that make a difference?  This is a national issue, not a local one!).  The Labour candidate replied, but only saw this as an education issue, while the Conservative candidate saw this as an issue of poor management of resources. 

Personally, I think this is an issue of short-term thinking. By not funding the research posts in higher education, a generation of scientists, engineers, mathematicians, and computer scientists will be lost forever to this country... some will go overseas, but most will simply drop out of their fields to find paying work in business.  Besides being a tremendous waste of educational investment, it also means that the brains this country needs to help pull this country out of recession will have gone elsewhere or long since left the cutting edge of their fields when the recovery occurs.  Its said that once a person leaves the sciences, they leave for good... I know personally that this is true, even if they want to return... and we are dooming a generation of newly-minted PhD's to essentially chuck away their expensive tax-supported education for lack of any other options.

Unfortunately, I don't think any of the parties really grasp that.  There are very few scientists... in fact very few people with any post-graduate technical education in the House of Commons.  Instead we have spin-doctors and party hacks, with no appreciation for the long-term future of this country


There seems to be a May holiday weekend tradition that every hiker with something to prove descends on the Three Peaks region of the Dales.  Not surprisingly, despite wind, hail, and a complete lack of training, long lines of gortex-clade pilgrims made their slow painful journey from Whernside to Ingleborough and from there on to Pen-y-ghent...  much complaining could be heard, as muscles that lay unused over the long winter were forced up one side of the mountain and then trudged painfully down the other...

In contrast, the quiet valley of Garsdale just to the north had nary a visitor...  just peaceful hiking, inquisitive ponies, and wildflowers waking to a late spring.

Primulus vulgaris, the common primrose could be seen in abundance in the low-lying portion of the valley, while Butterbur (Petasites hybridus) below was still in bloom in the marshy regions near the road.  In the Dales spring seems to have come late, as this plant has lost its bloom elsewhere.

Sunday, 2 May 2010

Signs of spring

An early arrival in the garden - the hoverfly Syrphus ribesii... in this case, a male settled on a dandelion in Yorkshire.

Pictures of hoverflies aren't too difficult to take... they like to settle on flowers and as they can easily escape predators, they usually allow you to get a camera into range. Identifying the hoverfly afterwords is a bit more challenging... fortunately Syrphus is an easily recognizable genus of hoverfly, as the UK has over 250 species to choose from.

Field forget-me-not (Myosotis arvensis), a common flower that appears on lawns in spring. Fortunately, also a very distinctive species.

Saturday, 1 May 2010

Threadfin Butterflyfish

So far I've posted two clips of fish that look like butterflyfish so this time I'm posting the real thing. This is
Chaetodon auriga, the Threadfin Butterflyfish, so named for that very thin "thread" coming off its dorsal fin.

Thursday, 29 April 2010

A brief detour from the reef

Just taking a little break from the tour of the museum to discuss my foray into the world of local politics.  I've just returned from a "hustings" with our four local candidates.  This isn't intended to be a political blog, but given the somewhat small turnout and the gravity of the topics under discussion I felt I needed to make a few comments on what I saw.

My main interest in attending was to see first hand our local MP, one Philip Davies (Con) who up to now I had heard little about, but was now regularly sending me flyers in which he made his fight against "political correctness" one of his main campaign planks.  Now, I can see why some people might think there is a bit too much political correctness, but its an odd thing to put in big letters on your campaign literature... and to be honest, in the part of the world where I come from, when a candidate talks loudly about political correctness he isn't advocating Chubby Brown play the Apollo... its a code word for the sort of soft racism that will let a black man sit at the front of the bus, so long as he doesn't have any asparations to drive it.  I was half expecting a posher version of Nick Griffin to be honest, and was somewhat pleasantly surprised to find that he didn't meet my initial expectation, but I have to say he reminded me very strongly of the American style right-wing rebel... a british John McCain if you will.

Now a bit of rebellion is a good thing - there are far too many yes-men elected to public office - but its only good being a rebel if you actually know what your talking about.  No real surprise, but Philip doesn't believe in global warming and even cited the East Anglia stolen emails as evidence, as though that was some silver bullet, clearly unaware of how East Anglia had been exonerated  from any wrong doing.  He was also a big fan of nuclear power, while at the same time he kept going on about the high cost of green technologies.... except aren't nuclear power plants very expensive to build, expensive to run, and even expensive to decommission? A glance at wikipedia (yes, I know...) indicated that the cost per reactor could vary between 100 million to 500 million euros or more.

Overall not a good sign from our local MP... its a short distance from rebel-without-a-cause to rebel-without-a-clue.

As for the other candidates...

John Harris (Lib Dem) came off as an academic... seemed to know his stuff, but his presentation skills could use some polish. I like that he is a biology teacher though... the more people in parliament with a grounding in science the better.

Kevin Warnes (Green) was much more polished, also a teacher, and has a PhD in political science... also seemed to know his stuff, and admitted that he is prepared to listen to the experts.  (though couldn't we get a few actual experts into the house, once in a while?)

Susan Hinchcliffe (Labour) came off well, but I can't help thinking she is pretty naive about her own party.  I think the funniest moment for me was when she mentioned the Freedom of Information Act as one of the good things Labour has done.  Now, I briefly worked in the civil service and one of the first things I was taught was all about avoiding FOI requests by not keeping records, self-censoring emails, selective minuting , and when all else fails, delay tactics. I'd be curious to see how aware she is of the inner workings of her own government, but then at the civil service we were quite good at hiding what we were really up to.

Wednesday, 28 April 2010

Also not a butterflyfish

No, this is a Moorish Idol (Zanclus cornutus) but you could be easily forgiven for this mistake.  It very closely resembles the Schooling Bannerfish (Heniochus diphreutes), the main difference being that Bannerfish are not as yellow and do not have as large and prominant black stripe behind the head. 

I followed this fast moving fellow hoping to get a nice side view, had to settle for just glimpses from above.

Monday, 26 April 2010

They come in pairs

Its not unusual to see pairs of fish swimming on the reef - in this case what I thought at first glance to be two damselfish turned out to be a pair of two-barred rabbitfish. Its interesting how they stayed together, despite being pursued by a giant potential predator (me). Not the first time that I saw paired fish moving together rather than splitting off in different directions.

Pairing behavior is better studied in some species of damselfish, where monogamous pairs of individuals will stay in close proximity on the reef, maintaining a territory and reacting antagonistically to any intruding fish from the same species. The pair of Blackback Butterflyfish (Chaetodon melannotus) I observed below seemed to be a pair, but later I saw a third Blackback come and join them without any conflict.

Sunday, 25 April 2010

Giant clams

One of the most fascinating creatures of the reef were the giant clams (Tridacna sp., Family Tridacnidae), which could be found both as large "free-standing" individuals or as smaller clams embedded in the coral. Amazingly, it used to be thought that divers could get themselves "trapped" by these clams, but when put to the test, I found that they closed slowly, and never completely.

Tridacna gigas, the classic Giant Clam, at Michaelmas cove, off of Cairns.

Tridacna gigas again, this time with the mantle retracted. Interestingly, these clams get about 70% of their energy from photosynthesis, due to symbiotic algae in the mantle.

This one is Tridacna crocea, a smaller species (this individual is about 10cm long) almost always found embedded in coral up to the margins. These were quite common in large coral heads, but easily overlooked if you weren't keeping an eye open.

Saturday, 24 April 2010

Hermit crab

What I first took to be an empty shell soon turned out to be occupied. Its not clear from the video, but this hermit crab is quite large - the shell is about the same dimensions as the palm of my hand.

This movie was taken at Trinity Beach, north of Cairns.

Green sea turtle

This fellow, a green sea turtle (Chelonia mydas) was seen off of Michaelmas reef, off the coast from Cairns. It was surprising how calm he was, considering that several divers suddenly appeared out of no-where and started chasing him with cameras.