Thermarces pelophilum – DC

The genus Thermarces, a type of fish with eel like characteristics, is typically the top predator in deep sea hydrothermal vent regions, concentrated to the aphotic bathypelagic zones. The bathypelagic zone is a stratified region of the ocean between 1000 and 4000m where light does not penetrate, and as such there is little primary production (hence why it is often called the midnight zone); this makes it a hostile environment suited only to few specialised species and extremophiles.

Organisms in the bathypelagic must be adapted to the lack of light, high pressure, low temperature and low oxygen levels. Their adaptations typically include slow metabolisms, unspecialised diets and low mobility in order to conserve the maximum amount of energy. The bathypelagic zone is inhabited by squid, large whales and octopuses (along with sponges and radiata) but it is difficult for fish to exist in these conditions. Fish that do exist here tend to be blind, with weak muscles, and soft bodies with a slimy exterior. Successful fish of the bathypelagic include the angler fish, or the bristlemouth. However, the even harsher and often toxic environments of hydrothermal vents is not suitable for these organisms, making Thermarces a dominant predator there.

Thermoregulation in Thermarces and other bathypelagic fish:
 * Sedentary – fish in the bathypelagic use slow movements with limited mobility in order to conserve maximum energy.
 * Blind – the lack of light counters the necessity of sight, therefore minimising energy expended on organisms with advanced sight
 * Homeotherms – stable but low temperature in deep sea due to lack of light. However, in hydrothermal vent regions this can fluctuated greatly.
 * Dynamic Feeders – for maximum intake of energy. Thermarces tends to feed on molluscs and crustaceans.
 * Slime Coat – keeps essential fluids and electrolytes in the fish, whilst keeping harmful material out