Category: invertebrates

Tiny sea creatures make huge, fantastic houses to protect themselves and get food

June 17, 2020 • 10:15 am

Of all the posts I’ve written about the amazing things animals do, testifying to the power of natural selection, this is one of the most amazing. It concerns a very tiny animal, Bathochordaeus stygius, a “giant larvacean”, which is a free-swimming marine tunicate, a chordate in the same phylum as we humans.  It’s about 1.5 inches (4 cm) long, with a “trunk” where the organs reside, and a tail that helps it swim and, in this case, pumps water to help it eat. The tail contains the notochord (a stiff rod that we have as embryos; it develops into our spinal column), as well as muscles that are crucial in the activity described here.

Here’s a photo of the naked tuncate from Ocean:

The larvacean is rarely found “naked,” however, for it builds not one but two houses for itself out of mucopolysaccharides (mucus), a big net-like house about a meter across as well as a smaller, complex house (about 10 cm or 4 inches across) in which the animal resides. And both houses are built and discarded every day!

A new paper in Nature, below, tells how researchers used a new laser apparatus in free-swimming animals off Australia to dissect the structure of the inner house to reveal its workings. That inner house, known for a long time, serves not only to protect the animal (it even has an escape hatch that it uses when discarding the inner house or when something bumps it), but mainly to concentrate small organic food particles, which, after being moved through several chambers by the tail undulations, wind up caught in a net by the trunk, where the animal eats it.

The group largely worked from the Monterey Bay Aquarium in California, which produced this wonderful 4-minute video summarizing the paper’s results:

 

You can also read a short summary at the New York Times, but it’s not all that great, leaving out really interesting information (don’t worry; I’ll supply it):

 

You can get the article free by clicking on the screenshot below (you must have the legal Unpaywall app), or find the pdf here. The full reference is at the bottom. And don’t miss the five videos, here, especially the one in which they use dye to track the water flow through the house.

The outer net (“oh”) in the (a) bit below, presumably serves (as does the inner house) to deter predators like fish and jellyfish, but also to catch larger food particles that the larvacean couldn’t eat and would clog the filter. It surrounds the inner house, which is quite complicated and serves mainly as a place to filter organic debris and convey it to the mouth of the larvacean. “si” in the first picture is an abandoned house; after being used for just a day, these sink to the sea floor where they and their food-particle contents are consumed by other animals. There are two channels between the outer “net” house and the inner house, allowing food to be transported neatly to near the larvacean:

(From Nature): a, Inner and outer house structures of the mucus feeding structure. b–e, White-light (b, c) and laser-sheet (d, e) illumination of both the lateral (b, d) and dorsal (c, e) views of a midwater giant larvacean, B. stygius. fcf, food-concentrating filter; ih, inner house; ihw, internal house wall; oh, outer house; si, abandoned house or sinker; st, suspensory thread; ta, tail; tc, tail chamber; tr, trunk. Scale bars, 4 cm.

The structures of the houses, particularly the inner houses, were determined using a “laser-sheet” apparatus called “DeepPIV”, shown below. This was put in the mid-level depths where the larvae reside and laser scans revealed sections of the houses, which were then assembled by computer to regenerate the three-dimensional structures.

Here’s a photo from the New York Times showing the DeepPIV in action:

And the result of the scanning.  The larvacean itself is seen in (a) and (b), with (b) also showing the filters by the head (trunk) where the animal can snack on what’s caught. Water comes in the two inlet channels (e), and then is moved by the flapping of the tail through two other channels that move the food to the filters.

 

Here’s the flow of water through the house as determined by both the laser scanning and dye-injection experiments that track water flow. It’s hard to see how the water moves (but watch the movies); thewater, after traversing the chambers, winds up flowing through two filters beside the head, where the larvacean takes the food. The filters get clogged up after a day or so, and the larvacean discards both the inner and outer houses and builds the two structures anew. That’s got to take a lot of metabolic energy!

And here is the BIG MYSTERY about this whole thing: how do they build the outer net and, especially, that complex inner house? After all, what we have here is essentially a tadpole without limbs, and yet somehow it’s able to construct two complex structures out of mucus, one inside the other. And I’ve bolded what really knocks me over from the paper’s summary:

The greatest remaining mysteries of larvacean houses concern how they are produced. Whereas a spider builds a complicated web one silky strand at a time, the house of a larvacean is extruded all at once as a rudiment and is then inflated. This leads to the question of how a bank of mucus-producing cells can create such an intricate form within a small, tightly packed bubble. Given their remarkable architecture, it seems almost implausible that these complex marvels should be built to last only a day or two. Future observational tools and vehicles will enable us to observe the construction of giant larvacean houses in their entirety, and to precisely document the frequency with which they are built.

It’s constructed compactly and then inflated! How on earth can this tiny creature do that? Well, we have no idea, so there’s lots of work to be done.  What is clear is that the houses, inner and outer, are examples of Dawkinsian “extended phenotypes,” structures that aren’t part of the animal’s body itself but can be conceived of as extensions of the animal (like a termite mound or a beaver dam) The behaviors for making the houses must clearly reside in the larvacean’s genome, as the animal doesn’t learn to do this. What a tangled house we build!

This is from Encyclopedia.com:

Larvaceans move their tail inside their house to make a current that filters food particles and moves the house through the water. If the filters become clogged or something bumps the house, the larvacean leaves the house through a trap door. The beginnings of a new house lie on the trunk of the animal’s body, and the larvacean inflates the new house and flips inside.

If you don’t find that stunning, you need to buff up your capacity for wonder!

Finally, just to show that this is by no means the largest invertebrate “extended phenotype” in the sea, here’s a video of a giant siphonophore (a class within the phylum Cnidaria, which includes jellyfish, corals, and sea anemones ) estimated to be 150 feet (46 meters) long. How the individual animals (“zooids”) work as a team, and the advantage of such a length, is yet to be determined.

This commentary is from SciTechDaily:

The discovery of the massive gelatinous string siphonophore — a floating colony of tiny individual zooids that clone themselves thousands of times into specialized bodies that string together to work as a team — was just one of the unique finds among some of the deepest fish and marine invertebrates ever recorded for Western Australia. Scientists from the Western Australian Museum, led by Chief Scientist Dr. Nerida Wilson, were joined by researchers from Curtin University, Geoscience Australia and Scripps Institution of Oceanography in exploring the Ningaloo Canyons in the Indian Ocean. Using an underwater robot, ROV SuBastian, they completed 20 dives at depths of up to 4,500 meters over 181 hours of exploration.

This all reminds me of biologist J. B. S. Haldane’s comment about the cosmos: “My own suspicion is that the Universe is not only queerer than we suppose, but queerer than we can suppose.” The “can” says everything about the limitations of our imagination. Nobody could ever have predicted or guessed that a larvacean like this could exist. Nor a frog, nor almost any other organism!

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Katija, K., Troni, G., Daniels, J. et al. 2020. Revealing enigmatic mucus structures in the deep sea using DeepPIV. Nature (2020). https://doi.org/10.1038/s41586-020-2345-2

Readers’ wildlife photos

June 6, 2020 • 8:00 am

During the pandemonium surrounding the entry of Honey and Dorothy’s broods into Botany Pond at the beginning of May, reader David Campbell sent me some wildlife pictures. And, as sometimes happens, I forgot to put them in the “readers’ wildlife” folder. He reminded me, and, with apologies, here are some late photos. David’s captions are indented:

Descriptions follow.  The Cannon Spring photo [last one] is not the highest quality but the situation was so unique that I thought some of your readers would be interested.

Dog Puke Slime Mold (Fuligo septica) A plasmodial slime mold that frequently occurs on mulch around plants after heavy rains.  The gross factor made it a big hit with my students when it appeared in the ornamental plantings outside my classroom.  It has no odor.  I am waiting for someone to come up with a Hairball Slime Mold.

Sailfin Catfish, Pterygoplichthys sp. Photographed in Silver Glen Springs in the Ocala National Forest of Florida.  Sailfins are exotic invasives that I have seen in a lot of springs in the St. Johns River basin.  Two species of Pterygoplichthys are found in Florida and frequent hybridization makes identification to species difficult.  Sailfin catfish are edible but they are encased in a hard, bony armor so cleaning them is difficult.  Some people simply cook them “in the shell” and peel them apart.

Blue Crab (Callinectes sapidus).  Blue crabs are anadromous, occurring in both fresh and salt water.  This one was photographed about 15 feet below the surface at the mouth of a freshwater spring in the Ocala National Forest.

Florida Gar (Lepisosteus platyrhincus) Gars look intimidating but are not aggressive toward swimmers.  This meter long fish swam over to examine me and then went back under nearby overhanging vegetation to do what gar seem to spend most of their time doing, sitting motionless in the water column.

Green Fly Orchid (Epidendrum magnoliae).  A native epiphytic orchid that is found as far north as North Carolina.  Different plants bloom at different times of the year, sometimes as late as December in Florida.  The flowers are quite small and easily overlooked but worth the effort to find.

Sidewinder (Crotalus cerastes).  Photographed in Arizona.  This is one of the smaller rattlesnakes and this individual was typically nervous and aggressive.  The right infrared sensing pit is visible forward of the eye.  Like many other pit vipers, sidewinders hunt at night and use infrared radiation from homeothermic prey in the final localization stage of hunting.

Monarch Butterfly (Danaus plexippus).  Two photos of a chrysalis, the pupa of this familiar butterfly.  These photo were taken three days after pupation.  The first photo was taken using conventional front lighting.  Clearly visible in the “skin” of the pupa are the outlines of wings, antenna, respiratory spiracles, and abdominal segmentation.  The second photo, taken during the same session, shows the chrysalis backlit.  Notice that the lower two thirds of the pupa is translucent with little or no visible structure.  Small clusters of cells are already organizing development of major butterfly organs and tissues from the products of broken down larval tissues.

Unicorn Caterpillar Moth (Schizura unicornis).  This is one of the more unusual Notodontidae caterpillars and was found feeding on an antique rose in the garden.  I moved it to a less valuable Cherokee rose where it continued feeding.  The adult is a nondescript little moth with a 25-35 cm wingspan.

Cannon Springs, Ocklawaha River, Florida.  This is a grab shot of something that is only visible for a month or two every three to four years.  Back in the 1960s the Army Corps of Engineers conceived and began construction on a barge canal connecting the Gulf of Mexico with the Atlantic Ocean, cutting across the Florida peninsula around the same latitude as Ocala.  One of the most beautiful rivers in Florida, the Ocklawaha was dammed to provide a wider and deeper channel for barges using the canal.  The resulting reservoir covered more than a dozen freshwater springs including several large ones.  President Nixon halted the canal construction before it could be finished but the dam remains and attempts to dismantle it and begin restoring the river have failed due to political resistance.

Every three to four years the Corps draws down the water level in the reservoir and, for a few weeks, several of the “lost” springs reappear.  Cannon is one of them.  I had planned on snorkeling here to photograph the fish and spring but I was the only human within miles and I never swim alone, especially when there is a five foot alligator sunning on the bank.  This photo was taken by holding the camera underwater as I floated nearby.  The larger of the two spring basins is in the background including the two vents where water flows out fast enough to keep the limestone clear of debris.  Also visible are several species of fish including lake chubsucker (Erimyzon sucetta), largemouth bass (Micropterus salmoides), chain pickerel (Esox niger), and bluegill (Lepomis macrochirus).  The spring is now submerged beneath four additional feet of murky brown water and won’t be visible again until at least 2023.

OLYMPUS DIGITAL CAMERA

 

Readers’ wildlife photos

May 29, 2020 • 7:45 am

Tony Eales from Brisbane has sent us a collection of mixed arthropod photos. His notes are indented:

I just thought I’d throw together some oddballs for fun.

First, a tiny little mite known as a whirly-gig mite family Anystidae. These guys are so small and fast that I rarely attempt to photograph them even if I see one. However this one stopped for half a second and I just managed to get the focus.

Next, a particularly pretty planarian worm called Australopacifica regina, found in the local subtropical rainforest under a log.

This is one of the cup moth or slug moth caterpillars. Calcarifera ordinata. The stings are said to be particularly fierce. Happily so far I remain un-stung, touch wood (actually don’t touch anything in the bush, it probably stings or bites, just take photos).

Next a few spiders. First, an undescribed member of the genus Celaenia. This genus generally imitate bird droppings though this one not so much. Still, it l doesn’t look very appetising.

Second an ant-mimicking jumping spider. Not as convincinga  close-up as the more well-known Myrmarachne species, but from above at a glance, it’s still very ant-like. This one is genus Ligonipes sp: .‘white brows’. A very common but as yet undescribed species.

The last spider is an Oonopid aka goblin spider. Maybe, genus Grymeus. I’ll know more later as there’s a person at the Qld Museum currently working on the family and I’m sending the specimen in to go into the collection. For fun I’ve added a picture of the spider in the test tube. See if you can spot it.

I picked up something fairly rare the other day, a species of lace bug, Tingidae. To me it looked like the fairly common pest known as the Azalea Lace Bug Stephanitis pyrioides but the experts said “Oh no, The shape of the hemelytron is distinctly different. This is an Australian endemic, Lepturga magnifica. In any case, it’s an interesting looking bug.

Weevils are so diverse and there are some extreme variations on the weevil bauplan. This is one of the odder ones Rhadinosomus lacordaireei or Thin Strawberry Weevil.

Last but not least, a weird offshoot of in the lacewing Order Neuroptera, a Beaded Lacewing in the family Berothidae. These are unusual within the Neuropterans for having particularly hairy wings. The one pictured is  Stenobiella sp. The larvae of these lacewings live in termite mounds, apparently unmolested, snacking on a passing termite when hungry. Wired did an article on how the larvae have been observed to paralyse the hapless termite with termite-stunning farts

 

Readers’ wildlife photos

May 8, 2020 • 8:00 am

We have two contributors today.

First, reader Martin Heller has several photos from the South Pacific. His notes (as with everyone’s) are indented:

Here are three pictures from my last stay in Bali (Jan-Mar 2020).

Preying mantis with prey, species unknown. The plant is a Giant Milkweed, Calotropis gigantea.

Colorful things growing on a stone in a tiny lava rock pond. Some fish in the lower left corner.

Cicak (house gecko), Hemidactylus frenatus, in a massage booth at the hotel pool.

From Garry VanGelderen in Ontario:

While in isolation (now going on for at least 5 weeks) I have been spending a lot of time in the alcove of the house. This alcove looks out on my backyard where I have several bird feeding stations and many trees. With few exceptions, these pictures have been taken through the glass of the windows.

Yellow-bellied sapsucker (Sphyrapicus varius), male:

Red-bellied woodpecker (Melanerpes carolinus), male:

Northern flicker (Colaptus auratus), male:
Downy woodpecker (Picoides pubescens), male:
Red-wing blackbird (Ageaius phoeniceus),male:

Wild turkey (Meleagris gallopavo), female:

And a bonus mammal (you guess it!):

Boston: Penguin Day visit to the Aquarium, and noms

January 21, 2020 • 11:00 am

As yesterday was Penguin Appreciation Day, we decided to visit the refurbished New England Aquarium, which has a lovely penguin exhibit, as well as many other nice exhibits. (They care well for their animals.) The penguin tank, which is huge, occupies the whole first floor of the aquarium, and, though it’s said to harbor rockhopper penguins and African penguins (Spheniscus demersus), we saw only the latter.

I saw rockhoppers in the Falkland Islands, but Africans are new to me. Here’s one in the Aquarium.

And here are two.

Luckily for us, it was penguin feeding time when we arrived. It’s a laborious exercise because, as you see in my video below, each tagged penguin is fed a precise number of fish by hand, and their consumption is tallied on a chart. Each fish is dipped in water before being proffered to the bird. This ensures that all penguins are well nourished, but I’m a bit sad that they don’t get the experience of catching fish on their own in the water. But that would have its own problems, including nutritional inequities.

A pair of them were mating—or trying to.

African penguins are also called “jackass penguins” because of their cacophonous braying. You can hear that in the video below.

Matthew sent me this tweet, which I’m just throwing in. I can imagine a penguin dating profile: “Natty dresser, loves long walks on the beach and fish dinners.”

They also had a couple of young cuttlefish in a tank, and I was mesmerized by them. They’re very smart, of course, but can also, like their relatives, change color quickly. They also have two “feeding tentacles” that shoot out instantly from the mouth region to snatch prey. You can see both the color change and the feeding apparatus in the video below.

Another hovering cuttlefish.

There was a lovely albeit small exhibit of jellyfish in a tank full of brine shrimp (I think). Here’s a photo and a video:

For lunch it was a short walk to the highly regarded Mexican lunch spot Tenóch near Davis Square.

It’s an unprepossessing place, serving tortas (Mexican sandwiches on fat rolls), tacos, and burritos. Their tortas are their best-known item.

The menu. I had the torta pastor with pork in achiote sauce, a big slice of fresh pineapple, pickled vegetables, cheese, and, well, look at the photo at the bottom and figure it out yourself. It was superb!

Unopened torta:

My sandwich, opened to show its contents. Yum!

I recommend this place highly if you’re near Davis or Porter Squares.

Readers’ wildlife photos

August 10, 2019 • 7:45 am

My photo tank is getting lower, so please send in your good wildlife photos. Today’s contribution is a passel of “semi-slugs” from Tony Eales, who hails from Queensland. His notes are brief. (I had no idea that there were “semi-slugs”! Since for some of these the shell can hardly be of any use for survival, perhaps some of these are in the process of losing their shells and evolving into “real slugs”.

According to Wikipedia, semi-slugs are “land gastropods whose shells are too small for them to retract into, but not quite vestigial. The shell of some semi-slugs may not be easily visible on casual inspection, because the shell may be covered over with the mantle.”

Israel colonizes the Moon

August 6, 2019 • 4:15 pm

Not satisfied with taking over the West Bank, Israel, in a clever plot probably orchestrated by Mossad, has sent Jewish animals, tardigrades, to the Moon. (Mossad has a well known history of using animals as spies or attack surrogates.) Since tardigrades can survive complete desiccation and low temperatures, their deposition on the Moon is a probable attempt to establish an Israeli foothold on another planet. After all, a Swedish scientist has shown that tardigrades are the only animal known to be able to survive in space for a minimum of ten days.

Well, the speculations above are clearly sarcastic, but, according to C|Net and other sources, a malfunctioning Israeli spacecraft has indeed, though accidentally, deposited tardigrades (“water bears”) on the lunar surface (click on screenshot, and for more see this article in Wired):

From the article:

Back in April, an Israeli spacecraft called Beresheet, which carried thousands of dehydrated tardigrades (among other cargo), crashed on the moon. Some people wondered if the water bears could survive.

One of those people was Arch Mission Foundation founder Nova Spivack. Arch Mission Foundation is a nonprofit whose main goal is to create a “backup of planet Earth.”

Well there you go! Just substitute “Israel” for “planet Earth” and you have it.  But wait! There’s more! They put human DNA up there, too, surely from Israelis:

The Israeli spacecraft was transporting Arch Mission’s first lunar library, a digital archive holding the equivalent of 30 million pages of information. It also carried human DNA samples and thousands of dehydrated tardigrades. It’s unknown how much of the cargo actually ended up on the moon’s surface following the crash.

Based on Arch Mission’s analysis of the spacecraft’s path as well as the makeup of the lunar library itself, Spivack told Wired on Monday that he’s confident the library, a “DVD-sized object made of thin sheets of nickel,” survived the crash mostly intact.

That doesn’t mean the DNA or water bears are in good shape.

“We sent enough DNA to regenerate life on Earth, if necessary,” Spivack tweeted Tuesday. “Although it would require more advanced biotech than we have to do that. At least our DNA is offsite now. But note that cells and DNA cannot survive or reproduce on the moon. Yet if retrieved they could be useful.”

“Useful” indeed—to create an apartheid planet! But wait—there’s still more:

“About the tardigrades in the Lunar Library: Some are sealed in epoxy with 100 million human, plant and microorganism cells,” Spivack tweeted Tuesday. “Some are encapsulated onto the sticky side of a 1cm square piece of Kapton tape that is sealed inside the disc stack. They cannot reproduce on the moon.”

Even though the dehydrated tardigrades can’t spring to life on the moon, they could theoretically be gathered, revived and studied to teach us about their time there.

“It is not likely that cells can survive on the moon without a lot more protection from radiation,” Spivack added. “However the human cells, plant cells and micro organisms we sent could be recovered, studied and their DNA extracted — perhaps to be cloned and regenerated, far in the future.”

Arch Mission Foundation, Nova Spivack and SpaceIL didn’t immediately respond to a request for comment.

That’s because these firms are probable covers for Mossad.

Seriously, the quotes and story are real; there are tardigrades and human DNA on the Moon. But I don’t think there was a good reason to contaminate the planet that way, even if there’s no chance of these things becoming alive. We don’t want to go mucking about with the Moon by filling it with organisms and nucleic acids.

Here’s a video showing how tough these critters are: