Why Evolution is True is a blog written by Jerry Coyne, centered on evolution and biology but also dealing with diverse topics like politics, culture, and cats.
This is the second part of a two-part batch of photos by Matt Young (part 1 is here). His IDs and captions are indented, and you can click on the photos to enlarge them.
I was in the Galápagos Islands during the end of December 2005, and the beginning of January 2006, bearing my trusty Canon PowerShot S30, with 3 megapixels and a 3X zoom. I took one or two pictures through an 8X monocular, but other than that I was on my own.
Mammals. The only mammals I saw, other than bipedal, were Galápagos sea lions, Zalophus wollebaeki.
A little snack:
And a nap:
Some geological features. Landscapes.
Lava tunnel. You could have easily crawled inside.
Today reader David Hughes sends us an unusual animal: a marine worm. Do not be grossed out at its appearance!
David’s captions are indented, and you can enlarge his photos by clicking on them.
Early last year you featured some of my Indian safari pictures on your ‘Readers’ Wildlife Photos’ section. For obvious reasons I haven’t been on any exotic trips over the past year and a half, but I thought I’d share some images of an animal I studied for several years. The photos are mostly scans of originals taken in the pre-digital era, so the quality isn’t great, but I hope they’ll be of interest. They show an animal that I’m certain none of your readers will have ever heard of, let alone seen.
This magnificent green blob has the equally magnificent scientific name of Maxmuelleria lankesteri. It belongs to a small group of marine worms called the Echiura [“spoon worms”]. Echiurans were traditionally classed as a distinct animal phylum (one of the so-called ‘minor phyla’ often lumped together in zoology textbooks). However, DNA analysis shows that they’re actually very weird annelid worms, so they’re now demoted to a subclass of the phylum Annelida. Echiurans are a pretty obscure group, not very familiar even to most marine biologists, but they’re found throughout the oceans, with different species found all the way from the intertidal zone to the deepest trenches.
The thicker section of the blob is the animal’s body. It’s basically a thin-walled bag with the consistency of a water-filled balloon. There are no internal segments, in fact nothing much at all inside apart from a long digestive tract, gonads, excretory sacs and a very simple nervous system. The thinner body section, looking like a pale green strap, is an extendible proboscis at the front end of the animal. The mouth is at its base. There’s no head or sense organs, and no hard parts other than a tiny pair of chitinous hooks on the anterior ventral surface. The worm’s body is quite fragile and specimens are usually crushed or fragmentary when collected. I was therefore very excited when this one came up intact in a dredge sample.
Maxmuelleria lankesteri is found around the western and southern coasts of Britain and Ireland, and off parts of Scandinavia. It’s especially common in the fjordic sea lochs along the west coast of Scotland. Its habitat is fine, organic-rich mud, where it occupies a burrow shaped like an extended “U”. The burrow cast shown in the photo was made by divers pouring epoxy resin down the holes at each end, leaving it to harden, then dragging it out by hand – a difficult and laborious process. The glove in the photo provides a scale, but some burrows extend much deeper than this one.
Maxmuelleria feeds by extending its proboscis out of one burrow opening, skimming-off the top layer of sediment as it goes, then withdrawing back into the burrow with its collected load. The accompanying photo is a screen-grab from a video camera placed over a burrow opening, and shows an extended proboscis in the lower-left quadrant. The animal ingests some of the collected sediment, and expels the rest out the other end of its burrow, creating a mound up to 30 cm high. Where these worms are common, the muddy seabed looks like a field of miniature volcanoes (below).
Apart from their overall weirdness, these worms have two particularly interesting features. The green colour comes from a pigment called bonellin (named after Bonellia, another echiuran genus). Bonellin is photoreactive, releasing free-radical oxygen when exposed to light. Oxygen radicals are highly destructive to the body wall tissues, so that like Count Dracula, Maxmuelleria literally falls apart and dies if exposed to sunlight. The specimen in the photos was only kept out long enough to have its portrait taken, then put into preservative. This sensitivity means that the animal only extends its feeding proboscis by night (video observations were made under infra-red light, which the worms can’t detect).]
Their life history is also odd. Big Maxmuelleria like the one shown here are all females, and in late summer, genital pouches full of eggs occupy most of the body cavity. In other species of the same family, the males are tiny dwarfs just a few millimetres long, which live in the genital pouches of the female and do nothing but fertilize her eggs. I always examined my collected Maxmuelleria specimens closely for dwarf males but never found any, so the reproductive biology of these worms is still a bit of a mystery. Small juvenile worms are also very rarely found – they’re nearly all whoppers like this one.
Apologies if this is a lot of text for a few photos, but this animal is so unfamiliar to most people that I thought it needed a bit more explanation than the usual birds and mammals. If anyone’s interested in the details of research into Maxmuelleria lankesteri, typing the name into Google Scholar will bring up quite a few papers on the subject, mostly written by me. Echiuran worms are a niche subject in marine biology, so I’m sure far more people read WEIT than have ever read my publications!
ZeFrank appears to have invited himself on a virtual NOAA (National Oceanic and Atmospheric Administration) “deep dive” from the Okeanos Explorer, a research ship that has a remotely operated vehicle (ROV) that can descend to 6,000 meters. A variety of videos reside on the NOAA website, and I suspect that ZeFrank took the video, with permission, from the site.
The goals of the Ocean Exploration mission are these:
With the mission to explore the ocean for national benefit, NOAA Ocean Exploration is the only U.S. federal organization dedicated to exploring the deep ocean. We are filling gaps in the basic understanding of U.S. deep waters and the seafloor and delivering the ocean information needed to strengthen the economy, health, and security of the United States.
The “conversation” you hear is the narration of the original videos combined with voiceover from ZeFrank, creating a “dialogue” between him and the Explorer personnel. Regardless, you’re here for the weird creatures that live in the depths of the ocean.
Send those photos in, please! We’re running low. Before we start, can anyone identify this raptor that perched over Botany Pond yesterday? The ducks were upset, quacked, and then formed a pack in the pond and remained very still. I took a photo, but it was hard because the bird was high up in a tree above the pond. So far we’ve never had a raptor attack a duck or duckling, but the adults still get freaked out when they see one.
Today we have a melange of California photos from Joe Dickinson. Joe’s captions are indented, and you can enlarge the photos by clicking on them.
We were visited this time by a turkey vulture (Cathartes aura).I believe the sunning of wings has to do with reducing parasite load, rather than drying the wings as cormorants do.
These photos of a fishing shack give some sense of the range of tides.
Nearby is the Point Reyes National Elk refuge with a nice population of Tule Elk (Cervus canadensis).
Mule deer (Odocoileus hemionus) also are found within the refuge as well as elsewhere on Point Reyes.
This moon jelly (probably genus Aurelia) actually is at a cabin on the other side of the bay where stayed a few years ago.
Nearby is the Marshall Store, home of the best BBQ oysters on the planet.
I call this the “Entropy Boat”.We have watched it slowly decay over the years.
There is a very nice walk to Kehoe Beach with this freshwater lagoon alongside.
Thanks to a slew of readers, we have enough photos for several potpourri features, but do send in your long-form contributions when you can. Thanks!
We’ll have two contributors today, the first being physicist and origami master Robert Lang from Altadena, California. Like all photos below, the captions are indented and you can enlarge the pictures by clicking on them:
I saw today you asked for a few topping-off photos, so I thought I’d send the below, from recent mornings’ hikes.
First, we have the common American Crow (Corvus brachyrhynchos). A group of these started hanging around my place for a few days; I suspect, coincidentally (and sadly) with the disappearance of the contents of a mourning dove nest I’d been monitoring in a nook above the back porch.
And now for a few hiking photos. The Whipple Yucca (Hesperoyucca whipplei) blooms in June, studding the mountains with cream-colored candlesticks. They bloom only once, then die, but there’s plenty of slightly younger ones to fill in each year.
Darkling Beetles (Eleodes sp., possibly armata) are fairly common around here. When disturbed, they stick their butt up in the air. This one was just going about its business.
And last, a new and uncommon critter: the Southern California legless lizard (Anniella stebbinsi). At first glance I thought it was an earthworm from its size and shape and the way it was twitching from side to side, but given the heat and dryness, any earthworm wouldn’t have been long for the world! A closer look revealed its reptilian scales, and then its stumpy tail and lizard-like head helped narrow it down.
Here are two photos by regular Joe Dickinson. He didn’t supply the IDs, but it’s clear that one is a flying fox and the other a primate. I’ll add the IDs when he responds to my query. In the meantime, you can guess!
Please send in your photos. I will probably put this feature on hold while I’m in Texas, but, except when I’m gone, the tank is always emptying.
Today’s photos come from regular Tony Eales, an anthropologist in Queensland who loves natural history. Tony’s captions and IDs are indented, and you can enlarge his photos by clicking on them.
Tropical North Queensland part II (part I is here)
Here are a few of the other wonderful organisms I encountered on my brief trip up north to the jungles.
Australian Prismatic Slug (Atopos cf australis). I’m pretty sure there are several species of this slug around, but they all seem to be labelled A. australis. They are predatory slusg with curved teeth in the radula, and they spit acid onto snail shells to help rasp through to the snail inside.
The tracks at Speewah Conservation Park were empty of other humans, which was great for spotting wildlife. I got to approach this Northern Tree Snake (Dendrelaphis calligaster) quite closely without alarming it too much. It’s a slightly built rear-fanged colubrid and presents no danger to humans.
These beautiful Tropical Rockmasters (Diphlebia euphoeoides), a type of flat-wing damselfly, were common around Cairns and the surrounding area. I wish we had such beauties near me. This photo shows a male and female at Lake Eacham.
This is a lichen-mimicking caterpillar, Enispa prolectus. These caterpillars fasten small pieces of lichen to their backs with silk as a form of camouflage.
As the area is a tropical rainforest and it was actually raining while I was there, I was inevitably attacked by many, many leeches. However, I spotted this one (Haemadipsa sp.) on a railing at night actively questing, and I was struck by the bright colours. I have to wonder, are these colours signals to each other, warning, camouflage or just random?
One for Mark Sturtevant: a Pisuarid spider, related to the Dolomedes triton that he featured recently. This one is Hygropoda lineata. These were very common in the north. Rather than living by the water, these spiders make a simple web platform across the surface of broad leaves and sit on top of it, often looking like they are hovering in thin air.
Nephila pilipes, the Giant Golden Orbweaver. These are well named. We have Golden Orbweavers at home, which are big spiders, but these northern ones are mind bending. This one had a body length of about 50mm and was eating a cicada the size of my thumb. The span of the web was about 6 metres from attachment to attachment and the main orb about a metre and a half across.
They are only weakly venomous to humans and very reluctant to bite even when handled, preferring just to climb away.
There were a huge variety of amazing ant species to be found in the forests, but by far the most common were the Green Weaver Ants,Oecophylla smaragdina. I was always checking their trails for signs of the spiders that mimic them. Unfortunately, I didn’t find any. I did however observe their interesting behaviour of holding leaves together like living stitches. Inside the ball of leaves larvae are being hatched. The larvae are then taken by workers and produce silk to tie the leaves together more permanently.
In Speewah Conservation Park there were lots of climbing palms, Calamus caryotoides. The mature stems are festooned with black spines to ward off herbivores. However, these caterpillars, which I’ve yet to ID, use the spines to create a protective home as the crawl around and eat the leaves.
These long-jawed orbweavers, Tetragnatha rubriventris, were very common around Cairns. They have massive hinged chelicerae and the males have large clubbed pedipalps with complicated spiralled spines for placing a sperm packet into the female epigynum. all this weirdness makes them great photo subjects for a really alien look.
Also in Speewah Conservation Park I found this amazing fruiting bodies of the slime mould Tubifera microsperma.
Imagine if Robespierre, after being guillotined during the Terror in France, was able to regrow his entire body just from his head alone. Well, that’s the equivalent of what some sea slugs can do, as reported in the new issue of Current Biology (click on screenshot below to access article, pdf here, and reference at the bottom).
In fact, two species of sacoglossan sea slugs, members of a group of shell-less mollusks, can not only grow a new body from just the head, but can do it twice in a row. Amazingly, the body that gets regrown includes the heart and the digestive system, which makes one wonder: how can they regrow a whole body without the nutrients gleaned from digestion? And how can the head live without a heart to supply it with oxygen. Well, that’s part of a very cool story.
Two Japanese researchers found that a substantial proportion (33%) of two species of sea slugs (Elysia cf. marginata and E. atroviridis) were observed in the laboratory to shed their own heads (“autotomy”, a fancy word for “self amputation”). Moreover, the heads regenerated new bodies—and quite quickly: within 20 days or so. The shed bodies, which did not regenerate new heads but died, contained the heart and the digestive systems. The heads, meanwhile, closed the wound after “voluntary” separation, began nibbling on algae within hours, and the regeneration of the entire body was done within three weeks.
Here’s a shot of four phases of the autotomy from the paper (as is the caption):
A) Head and body of Elysia cf. marginata (individual no. 1) just after autotomy (day 0), with the pericardium (heart) remaining in body section (arrow). (B) day 7, (C) day 14, (D) day 22, showing whole-body regeneration.
The 10 mm scale bar is about 0.4 inches. By day 22 they’re fully whole again, with a beating heart and a digestive system. See the green color? Those are algae that live in the mollusk’s cells: a key to how they might get the energy to regenerate.
Here’s a tweet with a video of the separated head and body. It’s just bizarre!
But wait! There’s more! The authors collected 82 sea slugs from the ocean that were all parasitized by the copepod Arthurius, which lives in the body (not the head) and inhibits the sea slug’s reproduction. Many of the parasitized slugs got rid of their bodies when brought to the lab. Here’s the parasite:
(J) Arthurius sp., the internal parasitic copepod of Elysia atroviridis.
This gives a clue as to why they’re ditching their bodies: to get rid of a parasite that lives in the body and impedes reproduction of the sea slug. Thus, it might be adaptive to discard your body along with a parasite, even if it takes substantial energy to regrow a new body.
Of 82 parasitized individuals collected from the wild, 41 shed their bodies. Of these, 13 regenerated those bodies, but the rest died. So there’s no guarantee that you’ll survive if you shed your parasite-laden body. But if you’re permanently sterilized by the parasite, or your reproduction is severely reduced, it may still be adaptive to take the chances and break apart; your net fitness may be higher that way. After all, the regenerated bodies, lacking parasites, are perfectly fertile.
More indication that this trait is adaptive is that these sea slugs have a “transverse groove” at their neck—the line where the breakage occurs. This implies that parasitism and body-shedding was a regular feature of the sea slugs’ past. Here’s the groove, which you can see if you look closely:
(I) Healthy individual of Elysia cf. marginata with a ‘breakage plane’ at their neck (dotted line).
When the authors tied nylon string around the groove, the slugs broke apart at this position, shedding a body that represents 80-85% of their total weight. When mock predator attacks took place, however, like pinching the head and cutting parts of the body, they did not break apart. This suggests that autotomy, if it’s an adaptation, is an adaptation to get rid of parasites and not to escape predators. (Many animals shed body parts when attacked, like lizards and salamanders that drop their tail when a predator grabs it.)
One question remains: where do the severed heads get the energy to regenerate an expensive body? The answer is another fancy word: kleptoplasty. Here’s how the authors explain it:
Why these sacoglossans can regenerate their body even if they lose most organs remains unclear, but we suspect involvement of kleptoplasty. In Elysia, a highly branched digestive gland is spread over the majority of its body surface, including the head, and the gland is lined by cells that maintain ingested algal chloroplasts. Thus, these sacoglossans can obtain energy for survival and regeneration from photosynthesis by kleptoplasts, even when they cannot digest food.
My question in response to this is: “do they get everything they need to regrow a body from the algal chloroplasts, including amino acids, sugars, and fats?” I suspect they do: where else could they get them? But perhaps a little digestion occurs in the mouth as well.
Where does this fit into biology? The phenomenon of autotomy is well known, as is the ability of many animals to regrow lost parts (you may have done such an experiment with flatworms when you were in high school). What’s unusual here is the regeneration of the entire complex body after it’s jettisoned, including the heart, which you would think was needed to keep the head alive! The authors say this:
Both Elysia cf. marginata and E. atroviridis shed the main body, including the heart. Some other sea slugs also autotomise, but they shed minor body parts such as tails, parapodia, or dorsal papillae. Other invertebrates (e.g., cnidarians, planarians, and asteroids) can regenerate their main body following division. Also, some amphibians are known to have a high regeneration capacity, including tails, limbs, eyes, and even the heart ventricle. However, autotomy in this study is remarkable in that animals with complex body plans can survive even if they lose the main body, including the heart, and subsequently regenerate the whole lost area. The reason why the head can survive without the heart and other important organs is unclear. We have succeeded in a complete rearing of Elysia cf. marginata for multiple generations — thus, they can be used as a model system for studying autotomy and regeneration of the body.
Now it’s no surprise that the animal has the potential to regenerate the body: after all, every cell in a sea slug contains all the genetic information necessary to produce another entire sea slug. But the trick is how to mobilize that information, which is usually inactivated in the wrong parts of the body. (We don’t activate the genes producing a liver, for instance, where our heart is supposed to be.) Somehow there is a mechanism here that makes the regenerating cells totipotent: capable of producing any part of the body starting at time zero. If we could figure out how they do this, we might be able to do it to ourselves, regrowing lost or diseased organs. But that is pure speculation; after all, we are not invertebrates—except for George Bridges at The Evergreen State College.
There are two places on Earth that constitute Vast Unknowns with the potential for finding new species. One, the tropical rain forest, is relatively easy to access, but the area is so vast and difficult of access that there is much to be discovered. And of course the tree canopies, which are rich with life, are not so easy to access.
The other place is the deep sea, particularly around and below the Antarctic continent. A new paper from Frontiers in Marine Science (click on screenshot below, pdf here, full reference at bottom), describes a batch of organisms, some with stalks, clinging to a rock beneath an ice shelf attached to the land. The interesting part of this study is not only the existence of life deep below ice shelves (that’s been seen before, including observations of fish, worms, anemones and mollusks), but life so far away from the open sea. What the eight researchers found was a group of stalked and nonstalked sessile organisms, probably sponges, clinging to a small boulder resting on the sea floor. The boulder was 260 km (160 miles) in from the edge of the Ronne Ice Shelf. (A shorter piece in the Guardian is here.)
This means not only are there sessile, filter-feeding organisms living far away from where the food comes from, but, even more striking, the currents that could bring detritus and microorganisms to those sponges are not from the closest open ocean, but from the opposite direction, since that’s where the currents come from. Given these currents, food for the observed species probably comes from between 625 and 1500 km (388-932 miles) away: the nearest open ocean that constitutes the source of photosynthesis that ultimately yields all the food. The researchers couldn’t collect the species, for they can be observed only through small holes bored with hot water through the thick shelf. Further, the big rock to which the organisms were affixed is 1233 m (4045 feet) below the ice. Given their remoteness, it’s almost certain that these species are new to science.
What’s striking about all this is that the total area explored by many researchers under the vast Antarctic ice shelves, which are so hard to penetrate, is smaller than a tennis court! Imagine what’s under there! This, however, is the first time that any sessile (immobile) organisms have been found on a substrate below an ice shelf. The remaining organisms involved—and there’s a table of them in the paper—are mobile (i.e., fish) or live on a soft, sea-bottom substrate.
Click to read the paper; I’ve put some videos of what they saw in the tweets below.
Here are the two great Antarctic ice shelves: the Ross and the Ronne (11 o’clock at the top), with the map taken from the paper. The places where the shelves have been penetrated by boring are indicated with dots: filled black dots show sites that yielded observations of organisms, while the sites showing no life have open (white) circles. The one spot below the Ronne shelf that produced the sessile and stalked organisms in this study is marked with a yellow star.
The animals, which are likely to be sponges but could be some other sessile or stalked organisms like ascidians, barnacles, or even worms or cnidarians, were affixed to a “drop boulder” about 1 x 0.75 meters across. How did it get there? The term “drop boulder” is a clue: this was probably a rock from the mountains on the continent itself that found its way into glacial ice, and then moved onto the ice shelf. At some point it fell through the ice and onto the sea floor. It then—only Ceiling Cat knows how—got colonized from another site.
Here’s the figure from the paper showing the boulder and its affixed organisms. They’re not very clear, and they’ve had to outline and highlight the organisms. I’ve added the caption from the paper
Dimensions and close-ups of the boulder, highlighting where life is clearly visible (A–E) and the top of the boulder where no obvious life is visible (F). The taxa visible on the boulder: Red, large stalked sponge; White, sponge; Orange, stalked taxa [possible sponge, ascidians, hydroid, barnacles, cnidaria (e.g., tubularia), and polychetes].Here are two videos, the first showing one of the scientists involved in the study explaining the find and its significance. The second video shows the organisms: the blobs on stocks are particularly clear. You can see the difficulties of trying to manipulate a probe and a light in the darkness through a borehole more than 4,000 feet above. But yes, those aren’t artifacts: they’re alive!
Discovery of life after drilling through 900m of Filchner-Ronne Ice Shelf in #Antarctica.
Another map shows the holes drilled in the immediate area and the direction of the sub-shelf currents in the vicinity. The hole that yielded the view of the boulder is FSW2. The black and purple arrows (see caption) indicate the direction of water flow, i.e., where the food comes from. As you see, the currents don’t flow from the nearest edge of the ice shelf but from a far greater distance, so the food particles have taken a circuitous route.
Map showing location of drill sites on Filchner Ice Shelf (FSW1-2, FSE1-2, and FNE2), comparable samples from continental shelf collected during JR275 as well as the major sub-ice shelf circulation. Black arrows show flows derived from High Salinity Shelf Water (HSSW) from the Ronne Depression. Purple arrow shows the flow from HSSW formed over Berkner Bank (Nicholls, 2004). Ice Shelf Water (ISW) exits along the eastern margin of Filchner Trough, with a possible seasonal influx of modified Warm Deep Water (mWDW) (Darelius et al., 2016). Dashed light blue arrows represent the flow of the slope front and coastal currents (Nicholls et al., 2009). Bathymetry is derived from ETOPO1 (NOAA National Geophysical Data Center, 2009).
The upshot: This is only a preliminary observation, and we don’t even know what those bloody creatures hanging onto the boulder are. But even observing them is a hard job: you have to get yourself onto the ice shelf with all your gear (perhaps they flew in), and then use a hot-water boring system to get through the thick shelf ice and then go down nearly a mile. To find out what these species are, they’d have to collect them, and that would involve either devising a boring/collecting device, or getting some kind of submersible below the shelf, most likely from above, which itself is nearly impossible. Going in below the shelf from the sea is theoretically possible, but it’s a big distance!
At any rate, what we know is that there are certainly many unknown species beneath the shelf, and maybe even unknown phyla. And once again we get the lesson that life is extremely tough and tenacious, here living in total darkness in near-freezing waters about a mile down, in an area where food is pretty damn scarce.
