Organisms
pharyngula | January 30, 2009Sepia erostrata
Figure from Cephalopods: A World Guide (amzn/b&n/abe/pwll), by Mark Norman.
pharyngula | January 29, 2009You've got to be impressed with the cephalopod-butchering skills of this dolphin. Especially be sure to check out the gallery of grisly photos.
I know, I like cephalopods. But I eat them, too!
pharyngula | January 23, 2009Mimic octopus
Figure from Cephalopods: A World Guide (amzn/b&n/abe/pwll), by Mark Norman.
pharyngula | January 19, 2009Sea squirts or ascidians are lovely little marine filter feeders. They have a larval tadpole stage, where the little guys disperse by swimming, and then they settle down, metamorphose, and spend the rest of their lives quietly sucking in sea water and filtering out small particles for food. They are soft, gooey little blobs that filter feed.
Except in Australia.
Everything seems to be toxic or dangerous in Australia. Newly discovered off the South Australian coast: carnivorous sea squirts. These creatures aren't content with living on bacteria or debris — they function like a Venus fly trap,…
pharyngula | January 4, 2009
Spiders are amazingly sophisticated animals, and probably the premiere complex adaptation of modern spiders is the ability to spin silk. They have multiple internal glands that can produce multiple kinds of silk — webs contain different kinds, from structural strands to adhesive strands, and other kinds are used for spinning egg cases and for wrapping prey — and they are sprayed out through small spigots mounted on swiveling spinnerets, which are modified opisthosomal (abdominal) limbs. Obviously, these detailed features did not spontaneously appear all at once, but had to have evolved…
pharyngula | December 23, 2008
Squid don't just make sperm: they package it up into fairly elaborate little torpedoes called spermatophores, which are either handed to the female with a specially modified arm called the hectocotyl arm, or squirted onto her with a penis. Once on the female (or a male, it really doesn't matter), the spermatophore everts, forming a structure called the spermatangia, in which all the packed sperm uncoil, ready to do their job, and the whole mass is anchored to the target with a cement body. These structures do show species-specific differences, but here is one example from Heteroteuthis…
pharyngula | December 22, 2008If I weren't so heavily invested in the cephalopods, siphonophores would be a great alternative.
pharyngula | December 12, 2008
(Image from Cephalopods: Octopuses and Cuttlefishes for the Home Aquarium(amzn/b&n/abe/pwll) by Colin Dunlop and Nancy King.)
pharyngula | December 4, 2008Representatives of the Antarctic and deep-sea genera of
octopuses. (a) Pareledone charcoti, a shallow-water species from the
Antarctic Peninsula. (b) Thaumeledone gunteri, a deep-water species
endemic to South Georgia. (c) Megaleledone setebos, a shallow water
circum-Antarctic species endemic to the Southern Ocean. Specimen
shown is juvenile; adults reach a total length of nearly 1 m. (d)
Adelieledone polymorpha, a species endemic to the western Antarctic.
All specimens illustrated are adult unless speciï¬ed and were collected
from the South Shetland Islands except T. gunteri from South…
pharyngula | November 28, 2008Megaleledone setebos
(from Strugnell, JM, Rogers AD, Prodo PA, Collins MA, Allcock AL (2008) The thermohaline expressway: the Southern Ocean as a centre of
origin for deep-sea octopuses. Cladistics 24:1-8)
pharyngula | November 26, 2008
Now this is an interesting beast. It's a 220 million year old fossil from China of an animal that is distinctly turtle-like. Here's a look at its dorsal side:
a, Skeleton in dorsal view. b, Skull in dorsal view. c, Skull in ventral view. d, Body in dorsal view. Teeth on the upper jaw and palatal elements were scratched out during excavation. Abbreviations: ar, articular; as, astragalus; ca, calcaneum; d, dentary; dep, dorsal process of epiplastron; dsc, dorsal process of scapula; ep, epiplastron; fe, femur; fi, fibula; gpep, gular projection of epiplastron; hu, humerus; hyo, hyoplastron; hyp…
pharyngula | November 18, 2008Once upon a time, way back when I entered graduate school, the first big project I was involved in was essentially a morphological mapping of the circuitry of the larval zebrafish. We did lots of backfills of neurons with horseradish peroxidase, and later the fluorescent dye DiI, and then with injected lineage tracers like rhodamine dextran. I guess technology has greatly advanced, because we never got anything as pretty as this set of fluorescently labeled neurons in the brain and spinal cord of a larval zebrafish.
(click for larger image)
This image was made using brainbow fluorescent…
pharyngula | November 17, 2008This is a spectacular video of the development of Clypeaster subdepressus, also called a sand dollar or sea biscuit. These are stunningly beautiful creatures (as are we all, of course), and it is so cool to see them changing here. The video starts with a little echinoderm porn — these animals are profligate with their gametes — and then we see early divisions, gastrulation, the formation of the pluteus larva, metamorphosis into Aristotle's lantern (one of the more charming names for a developmental stage), and into an ungainly spiky juvenile.
This is why some of us are developmental…
pharyngula | November 17, 2008
Christine Huffard sent me a note alerting me to the publication of her latest paper, and she thought I might be interested because I "seem to like cephalopods". Hah. Well. I've noticed that Dr Huffard seems to have some small affection for the tentacled beasties herself.
The paper follows on an old tradition and an old problem. While people have no problem distinguishing human individuals, we have a tough time telling one individual animal from another. This perceptual difficulty complicates problems of studying variations in behavior or physiology, or monitoring numbers and behavior, in…