Tail which the upper and lower lobes of tail fin are somewhat symmetrical and the vertebrae (backbone) flexes upward and partially extends onto tail fin. Found in gars. Intermediate between heterocercal and homocercal tails.
A small fleshy fin, lacking rays or spines, located on the midline of the dorsal surface between the dorsal fin and caudal fin.
A single, unpaired fin located along the midline of ventral surface between the anus and caudal fin. The anal fin may have spines and rays or just rays.
To the front.
The inner angle at which the pelvic or pectoral fin is joined to the body.
A bony splint or a modified scale extending from the upper or anterior base of a pelvic or pectoral fin.
A backward pointing projection, as on some spines.
A fleshy and flexible process, usually covered with taste buds, found near the mouth.
The part of a fin that is attached to the body.
Outer and inner fin rays longer giving a double concave shape; same as double emarginate.
Upper and lower lobes are rounded, middle rays slightly shorter, no deep V shape in center.
Pigmented spot with an indistinct outline or shape.
The greatest straight-line height or depth of the body, from the dorsal to the ventral surface.
Split into 2 or more extensions at the tip, as in some fin rays.
The area contains the gills, often also includes the throat.
Flexible membranes connecting the branchiostegal rays to each other and to the opercle. The branchiostegal membranes provide the seal that allows the movement of the gill cover and branchiostegal rays to pump water over the gills.
Thin bones located just posterior and ventral to the gill covers that support the gill membranes..
Long, pointed, conical tooth.
The base of the caudal fin (tail) where the vertebral column ends, which can be seen as a crease in the skin when the tail is flexed from side to side.
The tail fin.
The portion of the body between the posterior end of the anal fin base and the caudal base.
The portion of the head between the eye and the posterior edge of the preopercle.
A cell containing pigment.
A small fleshy or hair-like extension.
The external reproductive organs of male sharks and rays.
No separate tail fin, tail rays are continuous with dorsal and anal fins, as in some eels.
A pointed or rounded projection on the chewing surface of a tooth.
Something thin, flat and circular; the body of a ray.
Pertaining to the top (back) of the fish.
An unpaired fin located along the midline of the dorsal surface. It may have both spines and rays or just rays and consist of a single lobe, two lobes that are joined or separate, or a series of free spines and a lobe with rays.
A body or head shape in which the width is clearly greater than the depth and the fish looks as if it has been flattened from above.
Upper and lower lobes emarginate (concave), either with a notch between the lobes or rounded in the center (inner and outer rays longer); same as biconcave.
Slightly curved inward (concave), center rays slightly shorter than upper or lower rays.
A fin shape, in the dorsal fin or anal fin, in which the anterior few rays are noticeably and somewhat abruptly longer than subsequent rays, giving the edge of the fin a strongly curved (sickle-shaped) or concave profile
Tail fin shaped like a sickle, deeply concave, with the middle rays much shorter than the anterior or posterior rays.
A fold of skin supported by bony or cartilaginous rays or spines, used for locomotion, balance, steering, display, etc.
The extended or projected portion of fins, usually composed of elongated fin rays.
A small, isolated fin, usually found posterior to the dorsal or anal fin.
No tail fin, just fleshy knob, but not whip-like.
The straight-line distance from the most forward part of the head (or forward most tip of the lower jaw in billfishes) to the rear center edge or the innermost spot of the concave part of the tail.
Deep V-shaped center.
A filamentous respiratory organ which removes oxygen from water.
Bony or cartilaginous arch that support the gills, arranged in overlapping layers, and covered by the gill covers.
The flat bony plates that cover the branchial cavity and gills, consisting of the preopercle, interopercle, subopercle, and opercle; see operculum.
See gill slit.
Knobby or comb-like cartilaginous filaments extending anteriorly and inward from the gill arches. Used to sieve small food items from water passing over the gills.
Slit-like openings on the bottom (rays) or sides of fishes that lead to the gills. Most fishes only have one on each side behind the head. Sharks and rays have multiple pairs of gill slits.
A flat bone in the middle of lower jaw of certain fishes of ancient origin.
The straight-line distance from the most forward part of the head to the posterior end of the operculum (gill cover).
Upper lobe of tail fin is much longer than lower lobe with vertebral column (backbone) flexing upward and extending into the upper lobe of the fin, common in some sharks.
Upper and lower lobes of tail fin approximately symmetrical and the vertebral column ends at or near the middle of the tail fin base, not extending onto the fin. Homocercal includes all tail shapes (except in special cases) in which a tail fin is present
A mouth located on the ventral surface of the head and oriented downwards.
A ridge on the back of some sharks, running between the 2 dorsal fins.
The bony plate that lies beneath the lower edge of the preopercle. One of the 4 plates that make up the gill cover (operculum).
A fleshy process between the inner edges of the pelvic fins, in mackerels and tunas
The fleshy external area between the 2 gill cavities (throat or anterior breast area).
An opposable, articulated structure at the entrance of the mouth, used for grasping and manipulating food. The outer parts of the jaws in most fishes include the lower jaw (mandible) and the upper jaw (premaxillary, maxillary and supramaxillary).
Basket-like structure of over-lapping free branchiostegal rays used as support for the extended branchial region in some eels.
A relatively narrow and sharp ridge-like area of the ventral or dorsal surfaces or the sides of the caudal peduncle.
In some sharks, a U-shaped fold found at the corners of the mouth.
Middle rays longer than upper or lower rays and tapering to a point.
The sides of a body.
A sensory canal running along each side of many species having numerous openings or pores. The number of scales along the side with these pores (one pore per scale) between the posterior end of the opercle and the caudal base is the lateral line scale co
A body shape in which the body depth is more than the body width.
A flatfish in which the eyes are on the left side of the body, determined by the position of the eyes to the mouth.
The lower jaw of some fishes.
One of the bones of the upper jaw of fishes.
A cell of containing melanin (a dark pigment) found on the skin and fins.
A countable trait used to describe a particular species of fish, such as fin spines and rays or lateral line scales.
Areas of color with no particular shape or pattern.
The area on the back between the head and the dorsal fin.
Angled, either upward or downward, usually refers to mouths, stripes or lines.
A cavity or pit in the upper skull, behind the eyes; serves some sensory function.
In flatfish, the side (top) that the eyes are on.
The largest and posterior-most of the bony plates that make up the gill covers.
A bony plate that covers the gills
The anterior-most point where the fin connects with the body.
Oval in appearance, usually longer than wide or vise versa.
Patches of small teeth on that are found on each side of the roof of the mouth.
Paired fins located on the side of a fish just posterior to the gill covers.
Paired fins located on the ventral (bottom) surface either just anterior to the anus, underneath the pectoral fins, or just posterior to the throat.
A light-producing organ or spot.
Middle rays longer than upper or lower rays and tapering to a point.
To the rear.
A groove or notch on the upper area of the caudal base. Also called precaudal pit.
The area anterior to the dorsal fin.
The anterior-most bone in the upper jaw of fishes.
A groove on the head from between the eyes to the edge of the upper lip.
The anterior-most of the 4 bony plates that make up the gill cover (operculum).
A small spiny projection.
Refers to lips that can be extended or thrust out from the jaw and that are not rigidly connected to the upper jaw.
A segmented flexible support element of the fins, often branched at the tip; a cartilaginous fish that is flatten dorsoventrally and usually has a whip-like tail.
Rhomboid or diamond-shaped.
A flatfish in which the eyes are on the right side of the body, determined by the position of the eyes to the mouth.
A hardened snout that usually extends past the face.
Middle rays longer than upper or lower rays and posterior edge is rounded.
Small, undeveloped, primitive.
Blotch of dark pigment extending from the sides over the dorsal surface
A large hard scale, sometimes keeled, usually found on the sides along the lateral line.
In fish, the area around the upper end of the opercle.
The area from the tip of the head to the front of the eye.
The straight-line distance from the most forward part of the head to the front of the eye.
A dorsal fin or a portion of a dorsal fin that has no spines, only rays.
An un-segmented, rigid, support element of the fins, pointed at the tip, never branched; a rigid, pointed, usually flat bony process extending from the posterior edge of the opercles; a hard, sharp, serrated process on the base of the tail of stingrays.
In rays and some sharks, an opening on the head behind the eye through which water is drawn and passed over gills; aids the fish in breathing even when it is lying on the ocean bottom or buried in the sand.
Usually upper rays longer and pointed, middle rays shorter, and lower rays longer and curve shaped, giving an S shape; concave upper half, convex lower half.
The straight-line distance from the most forward part of the head to the end of the vertebral column (i.e. the caudal base) which can be seen as a crease in the skin when the tail is flexed from side to side.
The bony plate that lies posterior to the interopercle and below the opercle. One of the 4 bony plates that make up the gill cover (operculum).
A bony ridge from beneath the eye to the preopercle, usually has spines.
A mouth oriented and opening somewhat ventrally in which the upper jaw and snout clearly extend beyond the lower jaw.
A mouth where the lower jaw distinctly projects beyond the upper jaw and mouth opens upward.
A small bone on the posterior end of the upper jaw of some fishes.
A mouth where the lower jaw slightly projects beyond the upper jaw and mouth tends to open upward.
A gas-filled sac in the body cavity of most fishes, used as an aid to buoyancy.
A mouth opening at the anterior tip of the head in which the upper and lower jaws are approximately the same length with neither one extending beyond the other.
The area of the ventral surface below the branchial cavity and just anterior to the breast that includes the isthmus.
The straight-line distance from the most forward point of the head to the posterior tip of the caudal fin when compressed.
A more or less vertical edge.
A calcified and hard protuberance.
An area of enlarged scales behind the gill opening that can be vibrated to produce sound, in triggerfishes and filefishes
Pertaining to the underside or bottom of the fish.
Teeth found along the midline of the roof of the mouth.
Rounded in diameter, long and thin, no fin rays.