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 brief video shows the amazing camouflage of this tiny fish (yes, seahorses are fish; what else would they be?), and explores how scientists have been studying their reproduction and growth.
JAC: This is one way to determine whether a trait (yellow color) is hardwired genetically, or is simply part of the organism’s “norm of reaction”—in this case an evolved developmental program which can code for different but still adaptive outcomes in different environments (in this case, different color and ornamentation). It would be a nice experiment to rear the babies in a variety of different backgrounds, just to see how different they can become. It’s possible that, like octopuses, they can match a whole panoply of different substrates.
One issue: The video implies that the tubercles grown by the baby seahorses on purple sea fans matched the bumps on those sea fans. But I don’t see any difference in the shape of the tubercles induced by living on orange vs. purple sea fans. Maybe I’m wrong, but the video implies that mimicry can affect not only color, but tubercle shape.
Jonathan Wallace from England sent Jerry some amazing photographs of moths.
As always if you click through twice on a photograph you can see it in its original size.
Jonathan writes:
I thought I’d send you a few pictures around the theme of protective colouration in moths to help top up your tank.
First, two aposematic species, the Six-spot Burnet Moth (Zygaena filipendulae) and the Narrow-bordered Five-spot Burnet Moth (Zygaena lonicerae).
These moths are noxious to predators such as birds. As they are closely related I am not sure if they could be said to be mimics (as presumably they could both have inherited the same colour pattern from a common ancestor) but the two species do fly together in grasslands and presumably they reinforce each other’s aposematic signal in the manner of Mullerian mimics. There are a number of other Zygaena species all with variations on this same colour scheme.
Another two aposematic species the Garden Tiger Moth (Arctia caja). This species is widespread in the UK but has declined significantly in recent decades.
The Cinnabar Moth (Tyria jacobaea) has conspicuously striped larvae which feed on Common Ragwort (Sennecio jacobaea) from which they sequester toxins. The adults superficially resemble the Burnet Moths to which they are not closely related.
A final picture of a cryptic species. I guess a majority of moths, certainly in the UK rely to a greater or lesser extent on camouflage to avoid getting eaten. This one is a V-Pug (Chloroclystis v-ata) resting on a tree branch. I should state that this is not where I found the moth, which was caught in a light trap and I released it onto the branch. I was struck by how well it blended in.
Thanks Jonathan, for the beautiful photographs and the fascinating comments to go with them.
I am so glad that biologist Piotr Naskrecki gave me permission to post up his copyrighted photos without asking permission, because he takes some great pictures, and always tells us about the relevant biology. I’ve featured his work several times before (see this post on the cat mantis, for instance), but he just posted a picture on Facebook that stopped me in my tracks. It’s the praying mantis Idolomorpha dentifrons, and is featured in a post from August, 2013 on his biology-and-photography websiteThe Smaller Majority.
First, the photo (all captions are Piotr’s), taken in Mozambique’s Gorongosa National Park:
Male empusid (I. dentifrons) cleaning his pectinate antennae.
And a long photo, described thusly:
Earlier this year I ran across a gorgeous male specimen of Idolomorpha dentifrons on the Cheringoma Plateau of Gorongosa, but had troubles photographing it in a way that would properly convey its incredibly elongate morphology. In the end I took a series of vertical photos of its head and front legs that I stitched together in PS, and here is the result. Male empusids are unusual in having pectinate antennae, the kind usually seen in silk moths and other insects with well-developed pheromonal communication, where the female emits sex pheromones and males follow the faint scent trail. Not surprisingly, such behavior was recently demonstrated to be present in empusids (Gemeno et al. 2005. J. Ins. Behav. 18: 389-403).
A portrait of a male empusid Idolomorpha dentifrons from Gorongosa National Park, Mozambique. This photo is a composite of four vertical frames.
I’ll add one more photo of another bizarre species in the small family Empusidae: the striking Devil’s mantis:
The leaf-like morphology can be seen in the Devil’s mantis (Idolomantis diabolica), arguably one of the most striking and beautiful praying mantids in the world. The body of immature individuals resembles a dry, withered leaf, except for the brighter colors on the underside of the raptorial front legs. Adults turn pale green and white, and the pattern on their front legs becomes brightly red, resembling vivid petals of a flower. There is a reason for this – Devil’s mantids are specialized hunters of pollinators, such as bees and butterflies, and presumably this bright coloration fools some insects into coming dangerously too close.
I’m adding my authorship here as people automatically assume that every post whose title begins with “Spot the. . . ” is by Matthew Cobb. Over at Weather.com, of all places, there are a series of twelve photos, six showing cryptic snow leopards in the wild, each followed by a photo that circles the hidden cat. You’ll have to go over there to see if you’re right, but I’ll show three of the six photos.
Can you spot the Panthera uncia?
#1
A snow leopard is seen camouflaged against a mountain near the Indian Himalayas on Feb. 18, 2014. (David ‘Baz’ Jenkins/Caters News Agency)
#2
TWO snow leopards are seen camouflaged against a mountain near the Indian Himalayas on Feb. 18, 2014. (David ‘Baz’ Jenkins/Caters News Agency)
#3
A snow leopard is seen camouflaged against a mountain near the Indian Himalayas on Feb. 18, 2014. (David ‘Baz’ Jenkins/Caters News Agency)
We have a welcome break from hidden nightjars, for Reader Mark Sturtevant (whose photos of a caterpillar molting appeared this week), has a cryptic arthropod:
Today I have a small challenge for your readers. Somewhere in this picture is a rather well camouflaged 3 inch long caterpillar that is sitting in plain sight. Can your readers spot the caterpillar? This is one of many of this species that I found this summer. The first reader to find it will earn a nightjar point.
For an additional challenge, can the caterpillar be identified to species? This too may not be too difficult once the target is acquired. A hint is that this caterpillar lives in the U.S.
Click photo to enlarge. I’ll give the answer later today.
In about three weeks I’ll be giving a popular lecture on evolution in Bulgaria—that’s right, Bulgaria! I’m very excited, for who ever gets to go to that country? I will, and will spend a week travelling about, seeing the sights, consuming the local comestibles (including the famous yogurt), and, of course, meeting the local biologists.
They wanted a talk that would interest a general audience (it’s part of a public lecture series) but also teach them some evolution. Since I’m tired of the evidence-for-evolution talk, I decided to talk about mimicry. You know from my (and Matthew’s) many posts on the topic that I have a keen interest in it, as mimicry is not only one of the nicest examples of evolution by natural selection (no, Larry Moran, it can’t be due to genetic drift!), but one that shows how far natural selection can take an animal (or plant), despite various developmental and ecological constraints, to its “optimum”: looking like something else that you know. How close can it get? We know from the leafhoppers and frogmouths we’ve seen that it can get pretty damn close, not to mention Matthew’s blasted nightjars. There are other lessons about evolution to be learned from mimicry, too: things about frequency-dependent selection (polymorphic Batesian mimicry, failure to adapt (the hosts of cuckoos), and so on.
Mimicry is also a good topic for a show-and-tell talk, because there are so many stunning cases of it, which will wow an audience if they have the least interest in biology (just keep reading this site and you’ll see lots more).
And selection can take a species pretty damn close to where it “should” be. Case in point: the leaf fish Monocirrhus polyacanthus from Amazonia, an example I came across while preparing my talk. The fish has evolved both its appearance and behavior to mimic a floating leaf, all to get its prey. They are voracious hunters, and lightning fast in their nomming.
An incredibly-adapted species, this fish is camouflaged to mimic a dead leaf, both in body shape and pattern. It can change colour to match its surroundings and has a projection from its bottom lip that resembles a leaf stalk. When hunting, it stalks its prey in a head-down stance, appearing to drift towards it like a dead leaf drifting in a current. When it strikes at an item of prey the entire mouth protrudes outwards, forming a large tube into which the prey is sucked, usually head first. This happens so quickly it is often difficult to see. It can swallow prey almost as big as itself in this way.
A video of their behavior in an aquarium, which is anything but fishlike:
Here’s a video (with very annoying music) showing them hunting and eating:
And a photo of some specimens. The photos on the web show a variety of colors for this species. Notice that not only the mouth but the tail has evolved a point, so that the whole thing looks like a leaf:
I bet you didn’t know that there were leaf-mimicking fish.
[JAC: At least he’s off nighjars for the time being!]
by Matthew Cobb
This was tw**ted by Professor Dave Goulson of the University of Sussex, and was taken during a student field trip in Ecuador. How many moths can you see? (Click to enlarge)
Dave also tw**eted this picture of a mating pair of Arctiid moths, which he rightly suggests might be the most beautiful insects. The male is on the left, I guess (you can tell by his antennae):
Dave is the author of two excellent books, A Sting in the Tale, about bumblebees, and his recent A Buzz in the Meadow, to which I gave a rave review at New Scientist. Both are highly recommended.
