Lecture 2: Introduction to Fish Morphology - Vocabulary

Vocabulary flashcards covering external anatomy, fin structures, tail morphologies, body features, and standard measurements from the lecture notes.

fork length

Distance from the anterior-most point of the head to the caudal fin fork.

standard length

Distance from the tip of the snout to the end of the vertebral column (posterior to the hypural plate).

head length

Length of the head from the snout to the posterior edge of the skull.

fin spines

Rigid, spiny rays in fins that are not flexible.

soft dorsal fin

Dorsal fin composed of soft, flexible rays rather than spines.

snout

The anterior projection of the head; the front part of the face.

scale count

The number of body scales used for species identification.

premaxilla

Front bone of the upper jaw, often bearing teeth.

maxilla

Bone behind the premaxilla forming part of the upper jaw.

lateral line

A sensory canal running along the body to detect water movement and vibration.

preopercle

A bone forming part of the gill cover, located anterior to the opercle.

opercle

The bony plate that covers and protects the gills (gill cover).

interopercle

Bone forming part of the gill cover near the interopercular region.

subopercle

A bone forming part of the gill cover located ventrally under the opercle.

branchiostegals

Bony elements supporting the gill arches inside the opercular cavity.

pelvic fin

Pair of ventral fins located on the body’s belly region.

pectoral fin

Pair of fins located near the gills, used for steering and propulsion.

anal fin

Fin on the ventral side near the tail, behind the dorsal fins.

caudal fin

Tail fin; provides propulsion and varies in shape among species.

peduncle

The narrow segment of body between the body and the caudal fin.

dorsal fin

Fins on the back of the fish; can be spiny anteriorly and soft posteriorly.

adipose fin

Small, fleshy fin between the dorsal and caudal fins in some fishes; lacks spines.

spiny dorsal fin

Dorsal fin with spines at the front portion.

nares

Nostrils; openings on the snout used for sense of smell.

eye

Organ of vision located on the head.

mouth

Oral opening used for feeding.

scales

Protective plates on the fish skin; vary by species and body region.

hypural bones

Bones at the base of the caudal fin supporting the fin rays.

epural bones

Small bones near the caudal fin base on the dorsal side.

ceratotrichia

Keratinous, flexible fin supports found in cartilaginous fishes.

lepidotrichia

Bony fin rays found in ray-finned fishes; often segmented.

proximal radials

Proximal elements in the fin skeleton that support the fin rays.

actinopterygii

Class of ray-finned fishes.

chondrichthyes

Class of cartilaginous fishes (sharks, rays, skates).

gnathostomata

Jawed vertebrates.

sarcopterygii

Lobe-finned fishes (e.g., lungfish, coelacanths).

ostracodermi

Extinct group of armored jawless fishes.

heterocercal

Caudal fin with unequal lobes; vertebrae often deflected dorsally.

protocercal

Primitive tail where the fin rays originate from a common point; undifferentiated.

diphycercal

Caudal fin with two dorsal and ventral lobes that are often symmetrical.

homocercal

Caudal fin with roughly equal lobes; common in many teleosts.

isocercal

Tail with symmetrical lobes and axis; sometimes used interchangeably with homocercal.

ventral mouth

Mouth opens on the underside (ventral side) of the head.

subterminal mouth

Mouth located just behind the tip of the snout, oriented slightly downward.

terminal mouth

Mouth located at the tip of the snout.

superior mouth

Mouth oriented upward (upturned) on the snout.

total length

Distance from the tip of the snout to the end of the caudal fin.

postorbital length

Measurement from behind the eye to the posterior head region.

eye diameter

Width or height of the eyeball.

snout length

Distance from the tip of the snout to the posterior edge of the skull.

length of jaw

Measurement along the jaw from tip to joint.

prepectoral length

Distance from the tip of the snout to the origin of the pectoral fins.

length of anal fin base

Length along the body corresponding to the anal fin base.

length of caudal peduncle

Length of the narrow region just before the caudal fin.

length of pectoral fin

Measurement along the pectoral fin from base to tip.

length of dorsal fin base

Length along the back that corresponds to the dorsal fin base.