Biomedical Ephemera, or: A Frog for Your Boils

Doris sumptuosa [now Hexabranchus sanguineus] - "Spanish Dancer"

The "Spanish Dancer" nudibranch is named for its flamboyant "skirts" that swish around like a flamenco dancer. Hexabranchus sanguineus is found around the world, wherever the water is warm enough.

The species was first described based on a specimen from the Red Sea, where its coloration is almost blood-red (hence the "sanguineus" - blood-like). However, the color can vary from red, to orange, to bright yellow (though pure yellow is quite rare).

These are some of the largest nudibranchs out there. Adults can reach up to 40 cm in length.

United States Exploring Expedition, under the command of Charles Wilkes: Atlas, Mollusca and Shells. Augustus A. Gould, 1856.

Black Piranha - Serrasalmus rhombus

The black piranha (also known as the redeye or rhombeus piranha) has recently been discovered to have a bite force as strong as the estimated force of the extinct Megapiranha.

Though the negative stigma towards piranhas is largely undeserved, the mature black piranha is one of the most aggressive fish. This is especially true recently, with the over-fishing of the Amazon and Orinoco rivers, depleting the food sources of the adult fish.

Most species of juvenile piranhas feed on the scales and fins of others fish. Yes, they will swim up to, and rip the fins off of big fish, especially as they near maturity, but are not yet large enough to reliably hunt down other fish.

Despite their huge size (up to 1 m long, four times longer than adult black piranhas) and extremely strong bite force, the Megapiranha of the Pleistocene era (8-10 mya) wasn't believed to have a solely carnivorous diet. Their saw-shaped teeth bear similarities to the Serrasalmus genus, but also to the teeth of the Pacu, or "vegetarian piranha".

Expédition dans les parties centrales de l'Amérique du Sud, de Rio de Janeiro à Lima et de Lima au Para. Under direction of  Le Comte Francis de Castelnau, 1856.

Protopterus annectens annectens - West African Lungfish

Lungfish are fascinating!

They can grow up to over six feet long, and can either swim like eels, or crawl along the bottom with their thread-like fins. Since they generally live in shallow and oxygen-poor environments like swamps and marshes, the outpouching of the gut that acts as a swim bladder in other fish has actually developed into a lung.

Though they have full gills as hatchlings (and look like fishy tadpoles!), as adults, only the two anterior gill arches remain. The gill arches are too small to provide all of the oxygen that the fish needs, so the fish actually needs to gulp air from the surface to survive. During the beginning of the dry season, lungfish burrow into the bed of drying water and live in their mud nest until the rains come again.

Proceedings of the Zoological Society of London. 1856.

Fun fact: when camelids spit on you, that's not saliva. It's juice from their rumen...basically the partially-digested, half-fermented juicy bits from what they've been eating.

Grand Illustrated Encyclopedia of Animated Nature, embracing a full description of the different races of men. And of the Characteristic Habits and Modes of Life of the various Beasts, Birds, Fishes, Insects, Reptiles, and Microscopic Animalcula of the Globe. Being a Complete History of the Animal Kingdom by John Frost, L.L.D. 1856.