Mary’s Monday Metazoan: What? Females aren’t beautiful for me?

bluecrabfemale

That female crab doesn’t make herself gorgeous for the males of her species, it seems — sometimes a lady just has to look good.

Contrary to expectation, the model shows that winning the romantic interest of picky males is not enough to explain how desirable feminine features become widespread — even when better-looking females are more likely to land a good catch.

The results of their mathematical approach support other research suggesting that female beauty doesn’t evolve just to win mates.

Instead, traits such as the dance fly’s frilly legs or the blue crab’s red-tipped claws may help their bearers compete for other resources, such as social status or protection from predators. The results are consistent with an idea called the “social selection” hypothesis, first proposed three decades ago by theoretical biologist Mary Jane West-Eberhard of the Smithsonian Tropical Research Institute.

Impossible. They might consider other resources than access to my magnificent manliness to be valuable? Heresy.

Anti-Caturday post

Review the unpleasant nature of the cat’s penis. Now contemplate this: “12 feet long and highly mobile” and “gigantic testes that weigh a ton”.

Although, I do confess, when a pod of these big boys go into rut in your back yard, you’ll probably get even less sleep than when the neighborhood cats are in heat.

(Also on FtB)

The eyes of Anomalocaris

Look with your puny camera eyes! Some new specimens of Anomalocaris, the spectacular Cambrian predator, have been discovered in South Australia. These fossils exhibit well-preserved eyes, allowing us to see that the bulbous stalked balls on their heads were actually fairly typical compound eyes, like those of modern insects.

i-488c66eb96bbfef0beee7fdb0bf4f590-anomalocaris_eyes-thumb-500x418-71443.jpeg

Anomalocaris eyes from the Emu Bay Shale. a-d, Eye pair, SAM P45920a, level 10.4 m. a, b, Overview and camera lucida drawing. Scale bars, 5 mm. Grey fill in b represents visual surface, the proximal part in the upper eye extrapolated from the lower eye. c, Detail of ommatidial lenses located by horizontal white box in a. Scale bar, 1 mm. d, More complete eye, showing transition between visual surface and eye stalk (white arrows). Scale bar, 2 mm. e, Detail of ommatidial lenses in counterpart SAM P45920b. Scale bar, 0.3 mm. es, eye stalk; I.c., Isoxys communis; us, undetermined structure; vs, visual surface. Tilted white box in a represents area analysed using SEM-EDS.

The cool part of this discovery: the investigators were able to count the density of lenses and estimate how many were present in the intact eye. The number is 16,000 ommatidia in each eye, which is more than a little impressive: to put it in context, Drosophila has about 800. The emphasis on high-resolution vision suggests that Anomalocaris was diurnal predator in shallow water.

Oh, and just in case you’re one of those strange beings who isn’t instantly familiar with what the anomalocarids looked like, here’s a video to remind you.


Paterson JR, García-Bellido DC, Lee MS, Brock GA, Jago JB, Edgecombe GD (2011) Acute vision in the giant Cambrian predator Anomalocaris and the origin of compound eyes. Nature 480(7376):237-40.

(Also on FtB)

Anti-Caturday post

Usually, I try to accentuate the positive and tell you why other animals are so much more interesting than cats, but today I’m going right for the gutter and showing you why cats are evil. Behold, the cat penis:

You know who else has a penis like that? Satan.

Now you have another reason to get your cats neutered — so they don’t ever use that nightmarish thing.

(Also on FtB)