Keeltail needlefish
The keeltail needlefish is a unique species found primarily in the tropical Atlantic Ocean, distinguished by its broad lateral keels on each side of its caudal peduncle. These keels aid in maintaining balance while swimming, which is crucial given the fish's long, slender body that can reach lengths of up to 19.5 inches (50 centimeters). This species is also notable for its sharp, sword-like snout and tiny bluish scales on its back, with a paler underside. Keeltail needlefish are carnivorous, primarily feeding on smaller fish and crustaceans, and use their elongated jaws to spear prey rather than chewing. They typically inhabit shallow waters and are known to spawn in late spring and early summer, with a gestation period of 10 to 15 days for their eggs. Although they face predation from larger marine animals and birds, keeltail needlefish are not considered threatened and have a lifespan ranging from three to five years. Their presence can be observed near shorelines, making them a fascinating subject for those interested in marine life.
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Keeltail needlefish
The keeltail needlefish is the only species of needlefish in the western Atlantic Ocean with a broad lateral keel on each side of its caudal peduncle, or place where the body and tail meet. These keels help the fish to keep its balance in the water, preventing it from flipping over as its swims. The keelfish can also be found throughout the world's oceans swimming close to the shorelines.
Kingdom: Animalia
Phylum: Chordata
Class: Actinopterygii
Order: Beloniformes
Family: Belonidae
Genus: Platybelone
Species: Argalus
The keeltail needlefish generally grow to a length of about 19 1/2 inches (50 centimeters). It is the only western Atlantic species of needlefish with a broad lateral keel on each side of its caudal peduncle. The caudal peduncle is the part of the fish where the body meets the tail. In the case of the keeltail needlefish, this part is very depressed, or flattened. The keels, which look like flat projections, are aligned with, or arranged alongside, the fish's lateral line. A fish's lateral line is the line which runs horizontally along the fish's side. The purpose of these keels is to help the fish maintain its balance. Since the keeltail needlefish is a long, thin, stream-lined, needle-like fish, it needs more support to balance than most fish. The keels work together with the dorsal and anal, or back and belly fins, to keep the keeltail needlefish from accidentally turning over as it swims. The caudal, or tail, fin serves in the same manner as a ship's propeller, moving from side to side propelling the fish through the water. The keeltail needlefish also has a pair of pectoral, or side, fins and a pair of pelvic fins which paddle as it swims.
The keeltail needlefish has tiny bluish scales covering its back, and paler white scales on its belly. Like other needlefish, the keeltail needlefish has a long, thin beak, or snout, which projects from the rest of its body like a sword.
Since the keeltail needlefish does not have lungs and cannot process oxygen from the air, it has to find the oxygen it needs from its watery home. The keeltail needlefish takes water into its mouth, keeps the oxygen it needs, and pushes the waste chemicals out through the gills on the sides of its head.
The keeltail needlefish inhabits mainly oceanic waters of the tropical Atlantic Ocean. It generally swims near the surface of the water. The keeltail needlefish can also be found in areas of the Pacific and Indian Oceans.
As a carnivore, or meat-eating fish, the keeltail needlefish feeds on a diet of smaller fish and small crustaceans. It often spears its prey with its sharp jaws. Although the keeltail needlefish has many tiny, sharp teeth it does not chew its food before it swallows.
Mating season for the keeltail needlefish takes place in late spring and early summer. The female releases her eggs into the water and the male fertilizes them. This process of releasing and fertilizing eggs is known as spawning. After fertilization, the eggs begin drifting through the water. Their long, sticky filaments, or threads, soon attach to other eggs or floating seaweed. These eggs have a 10-to-15-day incubation, or growth, period before they hatch.
The keeltail needlefish is often preyed upon by larger sea animals such as tuna and dolphins. Because they swim close to the surface of the water, eagles, hawks, and ospreys may also prey on keeltail needlefish. Keeltail needlefish live between three and five years. They are not a threatened species.
Bibliography
“Needlefish Fish Facts - Platybelone Argalus.” A-Z Animals, 6 Apr. 2023, a-z-animals.com/animals/needlefish. Accessed 16 Apr. 2024.
Smithsonian Tropical Research Institute. “Species: Platybelone Argalus Argalus, Keeltail Needlefish.” Shorefishes - The Fishes - Species, 2023, biogeodb.stri.si.edu/caribbean/en/thefishes/species/3313. Accessed 16 Apr. 2024.