THE STEINHART AQUARIUM - Gulf of Guinea Science ...

100 A Docent Field Guide to the Species of the Steinhart Aquarium
some freshwater catfishes and sturgeon may
challenge this “record.”
One of the arapaimas is the largest fish in the
Steinhart by length.
Silver Arawana
Osteoglossum bicirrhosum (Osteoglossidae)
Bonytongues
Distribution: Northern South America: Amazon
River system.
Habitat: Benthopelagic, freshwater tropical,
24–30 °C. Especially prevalent in flooded areas
or swamps.
Appearance: Length to 1.2 m. Weight to 4.6 kg.
Body covered with very big scales; dorsal and
anal fins almost fused with the caudal fin. 2
barbels at the extremity of the lower jaw; adult
silvery. Juvenile with blue glints and a yelloworange
bar.
Diet: Feeds mainly on crustaceans, insects,
smaller fishes, and other animals that float on
the water, its upturned mouth an adaptation
for surface feeding. Arawana are also excellent
jumpers, and have been known to leap some
2 m out of the water to pluck a surprised and
often doomed insect or bird from overhanging
branches. Bats and snakes have also been occasionally
found as stomach contents.
Reproduction and Development: External
fertilization. Male carries eggs, larvae, and
young juveniles in mouth for about 2 months.
Elephant Nose
Gnathonemus petersi (Mormyridae)
Elephantfishes
Distribution: African Niger and Congo River
basins, mainly in the countries of Cameroon,
Nigeria and Congo.
Habitat: Turbid, muddy, bottom areas of fresh
tropical waters; prefers areas with submerged
wood for hiding places.
Appearance: Blackish/brown in color with a pair
of yellow-white vertical bands that extend from
the back of the dorsal fin to the anal fin. Elongated,
laterally compressed body with a round mouth
located at eye level and an extensible lower jaw,
hence the nickname, “Elephant Nose.”
This snout is its most unique feature. It is not
actually a nose, but an extension of the mouth
that is covered in electroreceptors that capture
information from the weak electric field the
fish generates. Receptors, which cover much
of the body as well, are used to navigate,
avoid predators, and find food and mates in
the turbid waters of its habitat. The caudal fin
is forked. Length to c. 30 cm.
Diet: This fish is a scavenger and uses its long
snout to dig and find worms and insects. The
elephantnose has poor eyesight, and depends
on the nose’s sensory receptors to find food.
Reproduction and Development: No external
differences between males and females.
Electroreceptors are also used to find a mate.
These fish are territorial and aggressive.
Remarks: Elephantnose fish have the largest
brain of any fish their size with a brain size
to body weight ratio higher than a human’s.
They have been used by water departments
in the U.S. and Germany to test the quality
of drinking water. When the quality of the
water declines, the amount of electrical pulses
released increases.
These fish are depicted in ancient Egyptian
tombs dating from 2500 BC.
ORDER ELOPIFORMES
(TARPONS)
Atlantic Tarpon
Megalops atlanticus (Megalopidae)
Tarpons
Distribution: Nova Scotia south to Brazil, Gulf
of Mexico, Caribbean. West coast of Africa.
Habitat: Inhabits coastal waters, bays, estuaries,
mangrove-lined lagoons, and rivers. Often
found in river mouths and bays.
Appearance: Length to 2.5 m. Weight to 160
kg. Large, elongate, moderately deep and
compressed body. Sides and belly silvery, back
blue-gray. Caudal fin deeply forked.
Diet: Sardines, anchovies, and other fishes;
shrimp, crabs, and other crustaceans.
Reproduction and Development: Spawn offshore.
High fecundity, a 2.3 m female estimated
to produce over 12 million eggs. Spawn in waters
which can be temporarily isolated from the open
sea. Larvae develop inshore and are leptocephalic
in shape (flattened, tansparent, and eel-like).
Mortality/Longevity: Individuals caught and
released by gamefishers are subject to injury.
Natural predators are sharks. Juveniles taken