Fish External Anatomy MVZ

Median Fins

Fins located along the midline: dorsal, caudal, and anal fins.

Paired Fins

Pectoral and pelvic fins.

Protocercal Tail

Primitive tail type where the vertebral column extends straight to the tip.

Heterocercal Tail

Tail where the vertebral column tilts upward into the larger upper lobe.

Homocercal Tail

Symmetrical tail where vertebrae end at the base of the fin.

Leptocercal Tail

Symmetrical, pointed tail with the vertebral column running straight to the tip.

Adipose Fin

Small, fleshy, rayless fin located behind the dorsal fin.

Snout

The region of the head in front of the eyes.

Barbels

Whisker-like sensory organs near the mouth used to feel and taste.

Operculum

Hard bony flap covering and protecting the gills in bony fishes.

Lateral Line

Sensory organ running along the side, detecting vibrations and water currents.

Caudal Peduncle

The narrow region of the body connecting the trunk to the caudal fin.

Ampullae of Lorenzini

Electroreceptors in Chondrichthyans used to detect weak electrical fields.

Placoid Scales

Tooth-like scales found in Chondrichthyans (sharks and rays).

Ganoid Scales

Hard, diamond-shaped scales found in primitive bony fishes like gars.

Cycloid Scales

Smooth, round, overlapping scales found in soft-rayed bony fishes.

Ctenoid Scales

Overlapping scales with tiny comb-like projections, found in spiny-rayed bony fishes.

Cosmoid Scales

Thick, heavy scales found in lungfishes and coelacanths.

Superior Mouth Position

Mouth points upward; indicates feeding on the surface.

Terminal Mouth Position

Mouth is at the front; indicates feeding on midwater prey.

Subterminal Mouth Position

Mouth points downward; indicates feeding on the bottom (benthic).