''Polypterus bichir lapradei'' is a subspecies of freshwater
fish
Fish are aquatic, craniate, gill-bearing animals that lack limbs with digits. Included in this definition are the living hagfish, lampreys, and cartilaginous and bony fish as well as various extinct related groups. Approximately 95% of li ...
in the family
Polypteridae
Bichirs and the reedfish comprise Polypteridae , a family of archaic ray-finned fishes and the only family in the order Polypteriformes .Helfman GS, Collette BB, Facey DE, Bowen BW. 2009. The Diversity of Fishes. West Sussex, UK: Blackwell Pub ...
. ''P. bichir lapradei'' are demersal, primitive, and popular with experienced aquarists.
Morphology
''Polypterus bichir lapradei'' is visually similar to its close relative, ''Polypterus bichir''. Its body is elongated and subcylindrical, and covered in
ganoid scale
A fish scale is a small rigid plate that grows out of the skin of a fish. The skin of most jawed fishes is covered with these protective scales, which can also provide effective camouflage through the use of reflection and colouration, as we ...
s. As its name suggests (''Poly'' = "many" and ''-terus'' = "finned"), ''P. bichir lapradeis most striking asset is the row of
dorsal fin
A dorsal fin is a fin located on the back of most marine and freshwater vertebrates within various taxa of the animal kingdom. Many species of animals possessing dorsal fins are not particularly closely related to each other, though through conv ...
lets along its back. These finlets, which can number up to 15 in some specimens, constitute a single dorsal fin. This fin is divided by rigid spines, which can be raised or lowered at will (often in response to a threat, or for stability).
This is a "lower jaw" bichir, meaning that its lower jaw is somewhat longer than its upper jaw (i.e. an underbite). Other "lower jaw" bichir species include ''
P. endlicheri'' and ''
P. ansorgii''. A commonly encountered "upper jaw" species is ''
P. senegalus''.
They have prominent external
nostril
A nostril (or naris , plural ''nares'' ) is either of the two orifices of the nose. They enable the entry and exit of air and other gasses through the nasal cavities. In birds and mammals, they contain branched bones or cartilages called turbi ...
s, which they use to great effect in compensating for their relatively weak eyesight.
''Polypterus bichir lapradeis coloration and patterning varies quite a bit region-to-region, but certain characteristics are almost always present. These include:
* Dark, longitudinal bands, punctuated by irregular, vertical stripes.
* Grayish green lateral and dorsal scales.
* Grey to white ventral coloration.
These bichirs use a coordinated network of
fins
A fin is a thin component or appendage attached to a larger body or structure. Fins typically function as foils that produce lift or thrust, or provide the ability to steer or stabilize motion while traveling in water, air, or other fluids. Fin ...
for
locomotion
Locomotion means the act or ability of something to transport or move itself from place to place.
Locomotion may refer to:
Motion
* Motion (physics)
* Robot locomotion, of man-made devices
By environment
* Aquatic locomotion
* Flight
* Locomoti ...
. Their
pectoral fin
Fins are distinctive anatomical features composed of bony spines or rays protruding from the body of a fish. They are covered with skin and joined together either in a webbed fashion, as seen in most bony fish, or similar to a flipper, as ...
s are used for general navigation---they help the fish turn, "brake", and "walk" across the bottom of their environment. When held rigid, the pectoral fins are strong enough to allow for short-distance travel across dry land. The
ventral fin
Pelvic fins or ventral fins are paired fins located on the ventral surface of fish. The paired pelvic fins are homologous to the hindlimbs of tetrapods.
Structure and function Structure
In actinopterygians, the pelvic fin consists of two en ...
s act as a keel would on a ship, keeping the bichir's subcylindrical body level. The
caudal fin
Fins are distinctive anatomical features composed of bony spines or rays protruding from the body of a fish. They are covered with skin and joined together either in a webbed fashion, as seen in most bony fish, or similar to a flipper, as se ...
, which connects directly to the dorsal fin, is the fish's primary means of propulsion. Although not a particularly fast species, ''P. bichir lapradei'' is capable of achieving quick bursts in pursuit of its prey (usually by folding all of its fins tightly against its body, and vigorously thrusting its caudal fin).
Bichirs are sexually dimorphic; the males are characterized by a fleshy, wide
anal fin
Fins are distinctive anatomical features composed of bony spines or rays protruding from the body of a fish. They are covered with skin and joined together either in a webbed fashion, as seen in most bony fish, or similar to a flipper, as se ...
, while the females' anal fin is thin and "sharp."
One of the most interesting characteristics of this (and every) bichir is the presence of a modified
swim bladder
The swim bladder, gas bladder, fish maw, or air bladder is an internal gas-filled Organ (anatomy), organ that contributes to the ability of many bony fish (but not cartilaginous fish) to control their buoyancy, and thus to stay at their curren ...
, which has evolved into a primitive
lung
The lungs are the primary organs of the respiratory system in humans and most other animals, including some snails and a small number of fish. In mammals and most other vertebrates, two lungs are located near the backbone on either side of t ...
structure. The "lung" is divided into two sections, and enables the bichirs to supplement their
oxygen
Oxygen is the chemical element with the symbol O and atomic number 8. It is a member of the chalcogen group in the periodic table, a highly reactive nonmetal, and an oxidizing agent that readily forms oxides with most elements as wel ...
intake by taking gulps at the surface of the water. This function has enabled them to survive in a great variety of water conditions. It also enables them to survive out of water, albeit for relatively brief periods of time.
''Polypterus bichir lapradei'' is a fairly large bichir species, reaching around 30" total length in adulthood.
Distribution
As with all of the
bichir
Bichirs and the reedfish comprise Polypteridae , a family of archaic ray-finned fishes and the only family in the order Polypteriformes .Helfman GS, Collette BB, Facey DE, Bowen BW. 2009. The Diversity of Fishes. West Sussex, UK: Blackwell Pub ...
species, ''P. bichir lapradei'' is endemic to Africa, where it can be found inhabiting numerous river systems throughout the continent.
References
Fishbase.org
{{Taxonbar, from=Q7226875
Polypteridae