The bighead searsid (''Holtbyrnia anomala'') is a
species
In biology, a species is the basic unit of classification and a taxonomic rank of an organism, as well as a unit of biodiversity. A species is often defined as the largest group of organisms in which any two individuals of the appropriate s ...
of
tubeshoulder
The tubeshoulders are a family, Platytroctidae, of ray-finned fish belonging to the order Alepocephaliformes. They are found throughout the world, except for the Mediterranean Sea. Tubeshoulders live at moderate depths of , and some have light-pr ...
fish.
Description
It maximum length is . Its head is large, making up over a third of the fish's length. It has 25–31
gillrakers; 5–11
pyloric caecae. The snout is pointed, with premaxillary tusks pointing forward.
It is dark red in colour. Its
photophore
A photophore is a glandular organ that appears as luminous spots on various marine animals, including fish and cephalopods. The organ can be simple, or as complex as the human eye; equipped with lenses, shutters, color filters and reflectors, ...
s are rudimentary (except for the shoulder organ), hence its specific name ''anomala'' ("unusual").
Habitat
The bighead searsid lives in the
North Atlantic Ocean
The Atlantic Ocean is the second-largest of the world's five oceans, with an area of about . It covers approximately 20% of Earth's surface and about 29% of its water surface area. It is known to separate the "Old World" of Africa, Europe an ...
; it is a
mesopelagic
The mesopelagic zone (Greek μέσον, middle), also known as the middle pelagic or twilight zone, is the part of the pelagic zone that lies between the photic epipelagic and the aphotic bathypelagic zones. It is defined by light, and begins ...
fish, living at depths of .
References
{{Rayfinned-fish-stub
Platytroctidae
Fish described in 1980
Bioluminescent fish