BryLog

Electric Fish Plug In To Communicate (via ScienceDaily)

The fish generate electric fields to navigate, fight and attract mates in murky streams and rivers throughout Central and South America. They do so at night, while trying to avoid predators such as catfish that sense the electric fields.

Generating electricity is costly (ask any homeowner paying for air conditioning during a hot summer), and the fish are using a dimmer switch to save energy by turning their electrical signals up and down, says Harold Zakon, professor of neurobiology….

They found that the dimmer switch comes in the form of sodium channels the fish insert and remove from the membranes of special cells, called electrocytes, within their electric organs. When more sodium channels are in the cell membrane, the electric impulse emitted by the electric organ is greater.

The scientists also show that the process is under the control of hormones. And it is maintained through a day-night circadian rhythm and can change rapidly during social encounters….

Ancient And Bizarre Fish Discovered: New Species Of Ghostshark From California And Baja California (via ScienceDaily)

Chimaeras, also called ratfish, rabbitfish, and ghostsharks, are perhaps the oldest and most enigmatic groups of fishes alive today. Their closest living relatives are sharks, but their evolutionary lineage branched off from sharks nearly 400 million years ago, and they have remained an isolated group ever since. Like sharks, chimaeras have skeletons composed of cartilage and the males have claspers for internal fertilization of females.

Unlike sharks, male chimaeras also have retractable sexual appendages on the forehead and in front of the pelvic fins and a single pair of gills. Most species also have a mildly venomous spine in front of the dorsal fin. Chimaeras were once a very diverse and abundant group, as illustrated by their global presence in the fossil record. They survived through the age of dinosaurs mostly unchanged, but today these fishes are relatively scarce and are usually confined to deep ocean waters, where they have largely avoided the reach of explorers and remained poorly known to science.

This new species belongs to the genus Hydrolagus, Latin for ‘water rabbit’ because of its grinding tooth plates reminiscent of a rabbit’s incisor teeth. This new species was originally collected as early as the mid 1960s, but went unnamed until this year because its taxonomic relationships were unclear. A large blackish-purple form, Hydrolagus melanophasma (melanophasma is Latin for ‘black ghost’), is found in deep water from the coast of Southern California, along the western coast of Baja California, and into the Sea of Cortez (Gulf of California). This species is known from a total of nine preserved museum specimens, and from video footage taken of it alive by a deep-water submersible in the Sea of Cortez….

A Fish with Humanoid Teeth (via Why Evolution is True)