While vacationing off the coast of Wales, I've been seeing a lot of jellyfish. In addition to the common moon jellyfish, there have also been large numbers of Blue Lion's Mane (Cyanea lamarckii), Barrel jellyfish (Rhizostoma octopus) and By-the-wind Sailors (Velella velella).
Cyanea lamarckii - Abersoch, Wales
Moon jellyfish and Blue Lion's Mane are not uncommon species, but this is the first time that I have seen By-the-wind Sailors. What surprised me the most is the size - the descriptions say that they grow up to 10 cm, but almost all that I saw were 1cm at best, although there were many of them. Occasionally I would see a larger one, but no longer than 2cm at most.
Velella velella - Harlech, Wales
There were large numbers of Barrel jellyfish close to the shores of Cardigan Bay - I counted almost 20 in three days, all but three of which were washed up on shore. They aren't supposed to be coming this close to the beach, but apparently these mass sightings do happen when the weather is unusually warm. The picture below was taken from the edge of the marina in Barmouth. Hopefully he managed to escape to deeper water before the tide retreated.
Diving season is back, no more quarries, actual sea life!
Most divers go for the rocky terrain, and why not? Lots of nooks and crannies for things to hide in, and good attachment surfaces for the more sessile marine dwellers. But this fellow I found in the open sand. This is a little cuttlefish (Sepiola atlantica) which was hiding in the sand until I disturbed it. To give some sense of scale, he is about the length of my thumb.
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.
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.
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.
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.
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.
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.
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.
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.
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.)
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!
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.
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.
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.
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.)
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.
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.
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.
