Category: mimicry and crypsis

A remarkable case of mimicry: Jumping spider imitates caterpillar

May 7, 2019 • 9:15 am

Tony Eales, who provided this morning’s mushroom photos, called my attention to this paper in the Israel Journal of Entomology, describing a remarkable case of mimicry seen in a newly described species of salticid (jumping spider). Click on the screenshot below to see the paper, or you can download the pdf here. It’s remarkable because, at least as far as I know, it’s the first known case of a spider mimicking a caterpillar—and the mimicry seems quite good. There are cases of caterpillars apparently mimicking spiders, like the monkey slug caterpillar, but this is the reverse situation.

The authors, one of whom (Logunov) is at the Manchester Museum at the University of Manchester and the other a citizen scientist in Hong Kong who may have spotted the beast and recognized it as new, describe a jumping spider found in, of all places, Hong Kong. It was first spotted on a metal railing in Shek O Country Park (see photo 9 below showing it it on the railing), with the single known male kept alive for a few days for observation before being preserved and sent to Manchester. They speculate that another specimen in a different museum might be an immature female spider of the species, but don’t know for sure. The authors believe, though, that other individuals of the species might occur in tree canopies, as do other species in the genus Uroballus.

The species was named Uroballus carlei, and the story of its name is cute:

Etymology: The species is dedicated to Eric Carle (b. 1929), the American illustrator and author of more than 70 books for children and adults. His most renowned books include ‘The Very Hungry Caterpillar’, which chronicles the growth and metamorphosis of a caterpillar, and ‘The Very Busy Spider’. Indeed, these and other books by Eric Carle provide the first conscious contact of young readers with the natural world, being innovative tools for early-age environmental and biodiversity education.

It’s a fuzzy spider with a thin abdomen and covered with hairs: here are dorsal, ventral, and lateral views from the paper:

(from the paper): Figs 1–7: Somatic characters and copulatory organs of Uroballus carlei sp. n. (holotype ♂): (1) body, dorsal view; (2) ditto, lateral view; (3) ditto, ventral view. Scale bars for Figs 1–3 = 1 mm

The one putative conspecific female in a museum differs by having a “wide brown serrate longitudinal stripe on the dorsum” and shorter spinnerets, so the species is not markedly sexually dimorphic.

The nice part is that the authors noted “a striking resemblance of live specimens of U. carlei to a small-sized hairy caterpillar (below). This similarity was noted in 2016 in this species by another researcher, who didn’t name the spider as a new species but put it in the genus Uroballus. (One other putative caterpillar mimic seems to be the salticid U. koponeni from Malaysia, but pictures aren’t given.)

The notion that U. carlei is indeed a caterpillar mimic comes from three considerations. First, it looks like a moth caterpillar (Brunia antica; shown in photos 16 and 17 below) that is found in Southeast Asia, along with similar-looking “lichen moth caterpillars”, which eat lichens and are found in Hong Kong. In particular, the skinny appearance of the spider and its dense and protruding hairs making it look caterpillar-like (the hairs in the caterpillars are “urticating” or irritating to predators).

So the possible sympatry of the model (caterpillar) and mimic (spider) is point number two. For this kind of mimicry to take place (see below), both spider and caterpillar have to live in the same place—at least during the evolution of mimicry. Finally, observations of the spider kept alive in the lab showed that “the male moved rather slowly and often stopped”, erecting its anal tubercle while moving.  This is not how most salticids move (they are quick and jerky), but it seems to resemble caterpillar movement.

Here is the putative model, U. carlei (8-15), and a member of the group of lichen moth caterpillars that it’s supposed to resemble (photos 16 and 17). It does look distinctly un-spider like, and, especially in photos 9, 12, and 13, caterpillar-like:

(from paper): Figs 8–17: General appearance of live male of Uroballus carlei n. sp. (holotype ♂; 8–15) and the caterpillars of Brunia antica (Walker, 1854) (16, 17). Scale bars = 1 mm.

So what kind of mimicry is this? It could involve three forms, all of which could have evolved roughly simultaneously.

Batesian mimicry.  Because the model caterpillars sequester lichen toxins in their body and are supposed to be distasteful, and also have irritating hairs, the spider could have evolved a resemblance to a caterpillar that is already avoided by predators who have learned that it’s toxic and distasteful.

Aggressive mimicry. There could be two forms of this:

a.) In the first, the spider would, by resembling a caterpillar, get close to prey who haven’t evolved an evolutionary fear of these caterpillars. (After all, the caterpillars eat lichens, not insects.) Salticids, though, are carnivores, and could jump on unwitting insects like flies and beetles who approach them thinking they’re just caterpillars.

b.) The authors observe that caterpillars are “prone to attack by specialized parasitoids” who lay their eggs in the caterpillars and then the hatched parasitoids, like tiny wasps, can eat the caterpillar from the inside. It’s possible that these salticids could also attract these parasitoids because the spiders resemble caterpillars, and then, when the parasitoids come to lay eggs on them, the spiders grab them and eat them.

As the authors note, the mimicry hypothesis requires a lot more work—both in the field and the lab. Do predators who learn to avoid the caterpillars also avoid the salticids? Do parasitoids attack the salticids in the lab and then get eaten? And do insects that have experience with caterpillars, and learn not to fear them, then approach the spiders and get eaten? All this, of course, depends on finding more of these spiders, as well as some of the caterpillars they’re supposed to resemble.

_______

Logunov, D. V. and S. M. Obenauer. 2019. A new species of Uroballus Simon, 1902 (Araneae: Salticidae) from Hong Kong, a jumping spider that appears  to mimic lichen moth caterpillar. Israel  Journal of Entomology 49:1-9.

 

Readers’ wildlife photos

March 9, 2018 • 7:30 am

Reader/biologist Jacques Hausser from Switzerland sends us another batch of lovely orthopterans (see here and here for parts I and II). Jacques’s notes are indented:

The third group of Orthopterans, the grasshoppers sensu stricto (suborder Caelifera) can be easily told apart from the Ensifera (bushcrickets/katydids and crickets) by their rather short and sturdy antennae and by the lack of a long ovipositor, replaced by four short chisels or burins allowing the female to bore a hole in the substrate to lay her eggs (Caelifera means “chisel bearer”). Their stridulatory and auditory equipment is also different: they stridulate by rubbing their hind legs against the elytrae, and their ears are located in the first abdominal segment. Grasshoppers are morphologically very homogenous (with exceptions!), and the coloration of most species is highly variable. The biblical locusts belong to this group.
Stenobothrus lineatus, the stripe-winged grasshopper, female. One can discern the dark eardrum just under the wing, to the right of the last green plate.
Mecostethus parapleurus, the leek grasshopper, male. This species likes reeds and other tall grasses in marshes and wet meadows. I don’t know what kind of relationship it has with leeks…
Chorthippus brunneus female, the common field grasshopper. It’s not obvious from this picture, but, like other mostly brown species, it prefers dry meadows with sparse vegetation.
Sphingonotus caerulans, the slender blue-winged grasshopper, and a well camouflaged one. The rear wings, hidden at rest, are pale blue (other related species have red hindwings), which makes it very visible in flight – but it instantly disappears when landing, fooling a would-be predator. Each time it moults, this spendid species can adapt its color to the environment – but it cannot change it between moults. It belongs to the subfamily of Locustinae together with the famous migratory locust.
Gomphocerippus rufus male, the rufous grasshopper, is easily recognizable by its black and white spatulate antennae. I call it the grasshoppers’ Pluto.
Same species, pairing. In grasshoppers the female is usually larger than the male.
Chrysochraon dispar, the large gold grasshopper. Like this one, females of several species are almost wingless, but the males keep fully developped wings, even if they are too short to fly—they need them to sing!
Another solution: they give up stridulating. Here is Miramella alpina, the green mountain grasshopper, a mountain species that replaces stridulation with grinding of the mandibles.
Acrida ungarica, the cone-headed grasshopper, a Mediterranean and East-European species. This is what happens to your head when the natural selection has decided that you should look like a bunch of twigs.

Monday: Hili dialogue

January 15, 2018 • 6:30 am

Good morning on a snowy Monday (January 15, 2018); I’ll have some snow pictures shortly. It’s holiday in the U.S. since it’s Martin Luther King Day (always the third Monday in January, and, as you’ll see below, it’s also King’s actual birthday). Here’s today’s Google Doodle about King.

Here are the final minutes of King’s famous “I have a dream” speech (full speech here), delivered at the March on Washington on August 28, 1963, a march shown in the Doodle. I’ve never heard a more stirring piece of rhetoric in my life, although some of Churchill’s wartime speeches come close. This was televised live to the nation, and I watched it.

This was King’s moment, and he took it big time. The Civil Rights Act of 1964 was passed the next year. I ask you to spare five minutes to listen to this, and remember that when it was given, there was still rampant and legal segregation in America:

It’s also National Pastrami Sandwich Day, which is weird because we just had National Pastrami Day. I sense the machinations of Big Pastrami.  And in Indonesia it’s Ocean Duty Day.

On this day in 1759, the British Museum opened. On January 15, 1870, Thomas Nast published in Harper’s Weekly a cartoon that first symbolized the Democratic party with a donkey. Here it is:

On this day in 1889, the Coca-Cola Company (then called the Pemberton Medicine Company) was incorporated in Atlanta, Georgia. Exactly three years later, James Naismith published the rules of “basketball.” On this day in 1919, two events happened: Rosa Luxemberg and Karl Liebknecht German socialists, were murdered by the Freikorps (German mercenaries); and the Great Molasses Flood occurred in Boston, an explosion that loosed a huge tsunami of the sweet stuff, killing 21 people and injured 150. On January 15, 1943, during WWII, the Pentagon was dedicated in Arlington, Virginia. On this day in 1967, the first Super Bowl was played in Los Angeles, with the Green Bay Packers beating the Kansas City Chiefs 35-10. And on this day in 2001, only 17 years ago, Wikipedia went online.

Notables born on this day include Molière (1622), Josef Breuer (1842), Osip Mandelstam (1891), Aristotle Onassis (1906), Edward Teller (1908), Gene Krupa (1909), Gamal Abdel Nasser (1918), mountaineer Maurice Herzog (1919), and Martin Luther King, Jr. (1929, assassinated 1968).

Those who expired on this day include Mathew Brady (1896), Karl Liebknecht and Rosa Luxemburg (1919; see above), Jack Teagarden (1964), Ray Bolger (1987), and Harry Nilsson (1994).

Teagarden is one of only two jazz trombonists I can name (the other is Juan Tizol of Ellington’s Band). He could also sing, and here he is with Louis Armstrong peforming the classic “Basin Street Blues” (Barney Bigard on clarinet):

Meanwhile in Dobrzyn, Hili is about to finish the last of the Japanese “cat’s snacks” sent her by Hiroko:

Hili: If I eat the last Japanese treat now, will I be sad later?
A: Probably.
Hili: Oh well, I will suffer later.
In Poliah:
Hili: Czy jak teraz zjem ten ostatni japoński przysmak, to potem będzie mi przykro?
Ja: Prawdopodobnie. 
Hili: Trudno, będę cierpieć.

A tweet from Matthew. Spot the longhorn beetle. (Translations of the Japanese welcome.)

And three more from Dr. Cobb:

https://twitter.com/historylvrsclub/status/952279620044369920

Be sure to watch the video. I’ve seen something like this in Scotland:

https://twitter.com/AMAZlNGNATURE/status/952554438421442560

A hedgehog comes alive when it smells food (h/t: Barry):

And a last-minute contribution by Grania:

A Müllerian mimicry ring

January 8, 2018 • 2:45 pm

Professor Ceiling Cat continues to be distressed at the lack of interest (reflected in comments, at least) on the science posts: those posts that are the hardest to write. Nevertheless, he persists.

Here is a likely example of aposematic (warningly colored) mimics in different orders of insects having evolved to resemble each other (tweet courtesy of Matthew Cobb).  This phenomenon is well known in biology, and is known as Müllerian mimicry after the German zoologist Fritz Müller.

If distasteful, noxious, or dangerous species share a common predator, they may evolve a convergent pattern or color that the predator recognizes and avoids. The presumed advantage is that if these species have a common pattern, the predator has to undergo less “learning” to recognize and avoid the shared pattern. What that means to one of these insects like those below is that if an individual of species 2 gets a mutation that somehow resembles a pattern that predators have already learned to avoid in species 1, it has a reproductive advantage over individuals of species 2 with some other aposematic mutation. Do you see why that is? It’s because the first few individuals of species 2 with a different aposematic pattern stick out in the environment, and the predator hasn’t yet learned to avoid them. Learning means that it has to sample the insect (likely killing it) before it learns to avoid the new pattern. You have a survival advantage if you fit in to an already-evolved/learned system rather that starting another one with a mutation that hasn’t been “learned.”

This, biologists presume, is the reason why members of different species evolve to resemble each other when they’re all noxious to predators.

Here we have species from three different insect orders—Coleoptera, Diptera, and Lepidoptera—which have evolve a common orange and black striped pattern.

While we can’t observe the evolution of this convergent pattern, we can make predictions from our evolutionary scenario.

First, these insects have to share a common predator: that is, there should be one or more species of predator that lives in the area that all these species inhabit, and has learned to recognize and avoid the pattern. That, of course, can be tested. (There are some twists here, but not important enough to mention.)

Second, that common predator has learned or can be taught to learn to avoid the pattern.

Third, if you have trained a predator (say, a naive, hand-reared bird) to avoid the pattern, introducing the predator to a different species with the same pattern should show that it’s avoided more often than a brightly colored species with a different pattern.

I know that the second prediction has been tested and confirmed for some aposematic insects, but I’ve no idea whether the first and third have been for members of Müllerian mimicry rings. (Hypothesis three has been tested and confirmed for members of singe aposematic species.)

The important thing is that the evolutionary hypothesis is testable. Creationists, of course, could just say “God made a group of insects this way so they’d survive”, but that assertion can lead to different predictions. I won’t go into those, but perhaps you can think of some.

Frog and snake: mimicry or not?

December 19, 2017 • 11:00 am

Julius Csotonyi, described by Wikipedia as a Canadian “paleoartist” (illustrator of ancient life) and a natural history illustrator, has done some fantastic artwork, including producing dinosaur images for Canadian coins. You can see a lot of his art at his website. But now Csotonyi may have detected a case of Batesian mimicry between a tree frog and a predatory snake (an emerald tree boa).

I’ll just show you his Facebook posts on the issue, which I have permission to put up. Julius sees a striking resemblance between the waxy monkey tree frog and a coiled emerald tree-boa, including the eyes, the folding of the skin, the color, and the white stripes.

The range overlap is some evidence for his thesis, though mimicry of a model can still have evolved when both now live in different places if the predator is migratory or if the mimicry is an evolutionary relic of a bigger range overlap that occurred long ago.  To me, the frog’s eyes, its posture, and the weird shape of the top of the head also resemble the snake.

I’m calling this a putative case of mimicry, but of course to be sure of this one would have to test it. For one thing, this is usually thought to work when the frog predator learns to avoid the snake through bitter experience, and then transfers that learning to avoiding the frog. If encounters of the frog predator with the snake were always fatal, no learning to avoid the snake appearance would be possible But predator avoidance could also be an innate response. That is, those frog-eaters who lived because they had genes that made them avoid approaching the snake because of its pattern,  and thus more likely to run away when they saw it, would be less likely to be eaten. That would produce an evolved rather than learned fear of things that look like this boa. Batesian mimicry need not always require a learned avoidance.

What do you think? Does this look like mimicry?  Put your answer below (we don’t know the truth, but herp people might take a guess). This may be the first case of Batesian mimicry involving an amphibian as the mimic and a snake as the model, but I’m not sure if other cases are already known.

As your reward for guessing, here’s another mimicry cartoon from SMBC (artist Zach Weinersmith) found by reader David.

Now what’s the erroneous assumption of this case of mimicry.?

Readers’ wildlife photos

December 7, 2017 • 7:30 am

Reader Tony Eales from Oz sent us some mimics; his words are indented. (See yesterday’s post on mantid flies.)

I photographed a couple of wild mimics yesterday. First was a large Mantis Fly, Euclimacia nuchalis, mimicking a large brown paper-wasp similar to this wasp.

Here’s the fly:

And the wasp (not Tony’s photo):

Also yet another ant-mimicking Jumping Spider (Myrmarachne sp.). I can’t stop photographing these.

Eight legs, not six!

But the weirdest was a jumping spider, Abracadabrella elegans, that mimics a fly’s face with its butt. It even runs backwards at times. I can’t for the life of me figure out why this mimicry occurs and all the sources are very hand-wavy about it.

The spider’s butt definitely resembles a fly, and this is likely a case of mimicry. But why???

Readers’ wildlife photos

August 16, 2017 • 7:30 am

Thanks to all for sending in photos, and remember that I’m always looking for good new ones. The first one today, sent by reader Hempenstein, shows a brown inchworm from Vermont, the larva of a geometrid moth. The resemblance to a twig is stunning:

Perhaps Lou Jost in Ecuador can help with this one, but if you know the insect, please respond in the comments below.

Reader John Conoboy sent some photos from a Galápagos trip. His notes are indented:

These are from a trip we took to the Galapagos in 2012. Unlike many Galapagos visitors we did not take a cruise, as I get seasick easily unless I am able to be outside in the fresh air where I can see the horizon. If I go below deck and the is enough movement, I get sick. We took a land-based trip through a New Zealand company called Active Adventures. Our guides and contacts were actually all from a Galapagos based company called Galakiwi, run by New Zealand ex pats. Our naturalist guide was superb. His name was Pablo and he was a big Darwin fan, so how could I not like him. I have read that the Seventh Day Adventists are working hard to convert people in the Galapagos and that it is possible to find guides there who are creationists. The downside of the trip was that we only got to the four islands that had settlements.

The Galapagos tortoise (Chelonoidis sp.) picture was taken at the Charles Darwin Research Station on Santa Cruz Island. I did not take good notes, so I think this is either Lonesome George, who we saw shortly before he died, or, more likely, Super Diego who has had much more breeding success than George, thus his name. I tried comparing this photo to some online photos of George and Diego but didn’t have much luck.

We spent a couple of nights on Floreana Island, which has a fascinating human history, fewer tourists, and, of course, interesting wildlife. I include two photos from the island. We saw couple of endemic Lava Herons (Butorides sundevalli) who posed nicely on a cactus (Opuntia sp.).

 Marine Iguanas (Amblyrhynchus cristatus)  are, I have read, black when young and more colorful as adults as this one on Floreana. I know there are a number of subspecies of iguana, but don’t know which this is. For anyone who is interested in Galapagos history, there is a fascinating documentary called “Galapagos Affair: Satan Came to Eden” It is a murder mystery involving the first European settlers, a German doctor (Ritter) and his mistress, the Wittmer family who moved there after reading Ritter’s writings about the island, and finally a self-styled baroness and her two lovers. It may still be available on Netflix.  The hotel we stayed at on the island is owned by the Wittmer descendants.

We took a hike to a cove on San Cristobal where people and endemic Galapagos sea lions (Zalophus wollebaeki) were enjoying a lovely beach together. This little sea lion was so cute and he posed nicely for a portrait.

It is easy to resist the sophomoric “I Love Boobies” t-shirts that are sold in all the gift stores. The real birds are much more appealing. My attention was on a couple of Nazca boobies (Sula granti) and did not immediately notice the blue footed booby (Sula nebouxii) on the right. This was taken at Kicker Rock, a very popular snorkeling site.

Lava lizards (Microlophus sp.) are everywhere. Here is one earning his name on San Cristobal Island, which would probably make him Microlophus bivattatus.

The sea lions love the harbor on San Cristobal and are found lying around on the piers, beaches, and even most of the benches near the water. The problem, of course, is that you have to be exceedingly careful about not stepping in sea lion poop, as I learned when walking on the beach while concentrating on taking photos.