Fish Terminology
See Also:
Glossary of Fish, Seafood and Fishing Terms
What is a Fish?
A Fish is a Limbless, aquatic, VERTEBRATE animal with fins,
internal gills, and skin with a glandular secretion that decreases friction. Most fish
have scales and are cold-blooded. A typical fish is torpedo-shaped, with a head containing
a brain and sensory organs, a muscular-walled trunk with a cavity containing internal
organs, and a muscular tail. Most fish propel themselves through water with weaving
movements and control direction with fins. Although some fish, such as sharks, bear live
young, most fish eggs are fertilised and hatch in water. There are over 20,000 species in
three classes: Agnatha, the most primitive fishes, jawless and without paired pelvic and
pectoral fins (e.g., LAMPREY); Chondrichthyes, cartilaginous fishes, with skeletons of
cartilage but no swim bladder or lungs (e.g., SHARK, RAY); and Osteichthyes, bony fishes,
the most highly developed. Bony fishes have a bony skeleton and a swim bladder or lungs,
and are divided into fleshy-finned (e.g., LOBEFIN, LUNGFISH) and ray-finned fishes (e.g.,
BASS, TUNA).
Adipose Fin - This fin most often occurs on characins. It is located forward
of the tail, (caudal fin) and behind the dorsal fin.
Alevin - A juvenile eel.
Amphipods - Amphipods (meaning "double life") are tiny
shrimp-like crustaceans that live in the water. They are marine invertebrates under an
inch long that have an exoskeleton and jointed legs. They are eaten in huge numbers by
filter feeders such as the whale shark, the basking shark, the megamouth shark, and baleen
whales.
Ampullae of Lorenzini - Sensory organs found around the heads of some
sharks.
Andromous - Fish that spend most of their lives in saltwater but migrate
into freshwater to spawn.
Anterior - Means located on or near the head or front of an animals body.
Anal Fin - A fin found behind the vent of most fish.
Barbel - Fleshy appendages often found on the mouths of certain fishes
such as carp, catfish, and loaches. These fleshy "feelers" are used to find
food.
Basihyal - A shark's tongue is called a basihyal. A basihyal is a small,
thick, relatively immovable piece of cartilage that is found on the floor of the mouth of
sharks and fishes. The basihyal seems to be useless for most sharks, except for the
cookiecutter sharks, who use it to rip "flesh-cookies" out of their prey
Bathypelagic - Bathypelagic means of, pertaining to, or living in the
deep ocean.
Bioluminescence - Bioluminescence is the production of light by living
organisms. Many deep-sea organisms are bioluminescent.
Brackish Water - This is a zone where salt and fresh water meet. It is
composed or varying amounts of salt and fresh water mixed together.
Carnivorous - Flesh eating.
Cartilaginous Fish - Non-bony fishes eg Sharks and Rays.
Caudal Fin - This is the tail fin of a fish.
Caudal Peduncle - This is the area of the fish where its tails meets its
body
Claspers - Claspers are modified organs that enable the two sexes to
clasp to one another during mating. Male sharks have claspers.
Concave - Inward curving (used to describe the tail shape)
Continental Shelf - The continental shelf is the part of the ocean floor
next to each of the continents. The sea floor slopes gradually from the continent to a
depth of about 100 metres. Beyond the continental shelf the sea floor drops steeply
Convex - Outward curving (used to describe the tail shape)
Crustacean - Hard shelled marine animal (eg. Crabs and Lobster)
Dermal Denticle - Tiny teeth that make up a sharks skin. Dermal denticles
are small, hard, tooth-like structures, also called placoid scales. They have the same
structure as a tooth, having an outer layer of enamel, dentine and a central pulp cavity.
Sharks' teeth and skin are composed of this type of scale.
Dorsal Fin - This is the fin that is located along the fishes back.
Exoskeleton - An exoskeleton is a tough, structural body armor made of
chitin. Crustaceans have exoskeletons.
Fingerling - An immature fish, fingerlings are usually larger than Fry
Fry - See Fingerling.
Gastropod - Gastropods are a class of mollusks that have a sucker-like
foot.
Gill - Breathing organ in fish.
Gill Rakers - Gill rakers are bristly structures (the bristles are about
4 inches or 10 cm long) in a filter-feeding shark's mouth that catch plankton which the
shark then swallows.
Gonopodia - This is the male sex organ of live-bearing fishes.
Gut - The intestines of a fish.
Hermaphrodite - Having the organs of both sexes.
Invertebrates - Animals without backbones. This can include corals,
snails, and shrimp or crabs.
Krill - A type of small, open ocean shrimp found in dense schools in cool
and temperate waters.
Labyrinth Organ - This is an organ that enables fish to obtain oxygen
from the air.
Larvae - Immature but active stage of growth.
Lateral Line - A row of sensory receptors along the flanks of some fish.
Milt - This is male fish sperm.
Mollusc - Soft-bodied, hard shelled animal. Also known as
shellfish. (eg. Oyster,
abalone and Mussel)
Native Fish - Those species which occur naturally in an area.
Nictitating Membrane - The white inner eyelid of some sharks which shuts
to protect the eye while fighting and feeding.
Nuchal Hump - This is an enlarged hump on some species of male fish.
Omnivorous - Eating all foods, both plant and flesh.
Operculum - This is the hard gill cover or the gill plates.
Otholiths - A pair of bones in the inner ear of fish which exhibit growth
rings. Also called the "jewel"
Pectoral Fins - Pectoral fins are the paired fins located behind the head
and on the lower side of the fish.
Peduncle - Where the body of the fish and the tail meet.
Pelagic - Any free-swimming oceanic species of fish such as tuna, marlin
etc.
Pelvic Fins -These are the fins that are located just forward of the anal
fin.
Plankton - Myriad forms of tiny marine life.
Rays - Fin rays are the bony support structures of the fins on a fish.
Roe - Fish eggs.
Sashimi - Japanese-style raw fish.
Scale - The small bony plates that cover most fish. They serve as a
protective skin against the environment.
School - A term used to identify a group of fish moving together.
Scutes - Sharp, modified scales along the lateral lines of some fish (eg.
Trevally and Yellowtail)
Shellfish - See Mollusc.
Spawning - A term that refers to the act of fish reproduction
Species - This is the scientific, taxonomic name of a living thing.
Subspecies - A scientific breakdown of organisms of a particular species.
Usually Subspecies are differentiated by small colour and location differences.
Substrate - The land below any water body. Sand, Gravel, and Mud are all
types of substrates
Swim Bladder - usually an air or fat filled organ that is used by fish to
maintain neutral water buoyancy. Also called Air Bladder.
Tentacle - Elongated, flexible organ of some animals (eg. Octopus) used for
grasping and feeding.
Vertebrate
any animal having a backbone or spinal column. All vertebrates belong
to the subphylum Vertebrata of the phylum CHORDATA. The five classes of vertebrates are FISH,
AMPHIBIANS, REPTILES, BIRDS, and MAMMALS. Vertebrates are comparatively large, have a high
degree of specialisation of their parts, and are bilaterally symmetrical. All have an
interior skeleton, a brain enclosed in a cranium, a closed circulatory system, and a heart
divided into two, three, or four chambers; most have two pairs of appendages modified as
fins, limbs, or wings in the different classes. Animals without backbones are called
INVERTEBRATES
