Bullseye electric ray
Encyclopedia
The bullseye electric ray or ocellated electric ray, Diplobatis ommata, is a species of numbfish, family Narcinidae
, native to the eastern Pacific Ocean
from Baja California
to Ecuador
. It is most common on sandy bottoms, but is also found over rocky bottoms, in bays, and near rock reef
s. The deepest reported occurrence of this species is at 94 meters (308 ft). This species is very similar to the variegated electric ray
(Diplobatis pictus), found in the Atlantic Ocean
.
This species grows to a maximum length of 25 cm (10 in). It has a rounded pectoral fin disk that overlaps the front margin of the large pelvic fins. The nostril
s on each side are divided into two apertures. The teeth are entirely covered when the mouth is closed. The two dorsal fin
s and caudal fin have rounded tips. The usual coloration is light brown above with numerous spots and diffuse, darker crossbars. There is a prominent ocellated marking at the center of the disk, from which this species derives its common name
. Some individuals are plain brown, with a large black spot at the center of the disk.
Like other numbfish, the bullseye electric ray is capable of generating a painful electric shock
for defense. It is a solitary, nocturnal species that spends the day partially buried in sand, near rock reefs. At night, it moves into shallower water, using its pelvic fins to "hop" along the bottom. It feeds on small crustacean
s such as amphipods and shrimp
, as well as polychaete worms. Females mature at under 18.5 cm (7.3 in) in length; the maturation size for males is unknown. Known parasites of this species include the cestodes Acanthobothrium dollyae, A. maryanskii, and A. royi.
Though not utilized by commercial fisheries
, the bullseye electric ray was assessed as Vulnerable
by the World Conservation Union
due to heavy trawling
activity throughout its limited range. It is caught as bycatch
in offshore shrimp trawls, and its catch rate is likely been underreported due to difficulties in identification.
Narcinidae
The numbfishes are a group of electric rays in the family Narcinidae. They are bottom-dwelling cartilaginous fishes with large, rounded pectoral fin discs and long tails...
, native to the eastern Pacific Ocean
Pacific Ocean
The Pacific Ocean is the largest of the Earth's oceanic divisions. It extends from the Arctic in the north to the Southern Ocean in the south, bounded by Asia and Australia in the west, and the Americas in the east.At 165.2 million square kilometres in area, this largest division of the World...
from Baja California
Baja California
Baja California officially Estado Libre y Soberano de Baja California is one of the 31 states which, with the Federal District, comprise the 32 Federal Entities of Mexico. It is both the northernmost and westernmost state of Mexico. Before becoming a state in 1953, the area was known as the North...
to Ecuador
Ecuador
Ecuador , officially the Republic of Ecuador is a representative democratic republic in South America, bordered by Colombia on the north, Peru on the east and south, and by the Pacific Ocean to the west. It is one of only two countries in South America, along with Chile, that do not have a border...
. It is most common on sandy bottoms, but is also found over rocky bottoms, in bays, and near rock reef
Reef
In nautical terminology, a reef is a rock, sandbar, or other feature lying beneath the surface of the water ....
s. The deepest reported occurrence of this species is at 94 meters (308 ft). This species is very similar to the variegated electric ray
Variegated electric ray
The painted electric ray or variegated electric ray, Diplobatis pictus , is a poorly-known species of numbfish, family Narcinidae, native to the western Atlantic Ocean from southeastern Venezuela to the mouth of the Amazon River in Brazil. It is common on soft substrates at a depth of 2-120 meters....
(Diplobatis pictus), found in the Atlantic Ocean
Atlantic Ocean
The Atlantic Ocean is the second-largest of the world's oceanic divisions. With a total area of about , it covers approximately 20% of the Earth's surface and about 26% of its water surface area...
.
This species grows to a maximum length of 25 cm (10 in). It has a rounded pectoral fin disk that overlaps the front margin of the large pelvic fins. The nostril
Nostril
A nostril is one of the two channels of the nose, from the point where they bifurcate to the external opening. In birds and mammals, they contain branched bones or cartilages called turbinates, whose function is to warm air on inhalation and remove moisture on exhalation...
s on each side are divided into two apertures. The teeth are entirely covered when the mouth is closed. The two dorsal fin
Dorsal fin
A dorsal fin is a fin located on the backs of various unrelated marine and freshwater vertebrates, including most fishes, marine mammals , and the ichthyosaurs...
s and caudal fin have rounded tips. The usual coloration is light brown above with numerous spots and diffuse, darker crossbars. There is a prominent ocellated marking at the center of the disk, from which this species derives its common name
Common name
A common name of a taxon or organism is a name in general use within a community; it is often contrasted with the scientific name for the same organism...
. Some individuals are plain brown, with a large black spot at the center of the disk.
Like other numbfish, the bullseye electric ray is capable of generating a painful electric shock
Electric shock
Electric Shock of a body with any source of electricity that causes a sufficient current through the skin, muscles or hair. Typically, the expression is used to denote an unwanted exposure to electricity, hence the effects are considered undesirable....
for defense. It is a solitary, nocturnal species that spends the day partially buried in sand, near rock reefs. At night, it moves into shallower water, using its pelvic fins to "hop" along the bottom. It feeds on small crustacean
Crustacean
Crustaceans form a very large group of arthropods, usually treated as a subphylum, which includes such familiar animals as crabs, lobsters, crayfish, shrimp, krill and barnacles. The 50,000 described species range in size from Stygotantulus stocki at , to the Japanese spider crab with a leg span...
s such as amphipods and shrimp
Shrimp
Shrimp are swimming, decapod crustaceans classified in the infraorder Caridea, found widely around the world in both fresh and salt water. Adult shrimp are filter feeding benthic animals living close to the bottom. They can live in schools and can swim rapidly backwards. Shrimp are an important...
, as well as polychaete worms. Females mature at under 18.5 cm (7.3 in) in length; the maturation size for males is unknown. Known parasites of this species include the cestodes Acanthobothrium dollyae, A. maryanskii, and A. royi.
Though not utilized by commercial fisheries
Commercial fishing
Commercial fishing is the activity of catching fish and other seafood for commercial profit, mostly from wild fisheries. It provides a large quantity of food to many countries around the world, but those who practice it as an industry must often pursue fish far into the ocean under adverse conditions...
, the bullseye electric ray was assessed as Vulnerable
Vulnerable species
On 30 January 2010, the IUCN Red List of Threatened Species identified 9694 Vulnerable species, subspecies and varieties, stocks and sub-populations.-References:...
by the World Conservation Union
World Conservation Union
The International Union for Conservation of Nature and Natural Resources is an international organization dedicated to finding "pragmatic solutions to our most pressing environment and development challenges." The organization publishes the IUCN Red List, compiling information from a network of...
due to heavy trawling
Trawling
Trawling is a method of fishing that involves pulling a fishing net through the water behind one or more boats. The net that is used for trawling is called a trawl....
activity throughout its limited range. It is caught as bycatch
Bycatch
The term “bycatch” is usually used for fish caught unintentionally in a fishery while intending to catch other fish. It may however also indicate untargeted catch in other forms of animal harvesting or collecting...
in offshore shrimp trawls, and its catch rate is likely been underreported due to difficulties in identification.