Ichthyology Lecture: Introduction to Fish Diversity & Biology

Vocabulary flashcards covering key concepts, anatomy, reproductive modes, and classification of marine and freshwater fish from the lecture notes.

Agnathans

Jawless fish characterized by circular, muscular mouths lined with keratin teeth and an absence of articulating jaws.

Chondrichthyes

The class of fish possessing a skeleton made of cartilage rather than true bone, including sharks, rays, skates, and ratfish.

Osteichthyes

The major group of fish characterized by skeletons made of true bone.

Pectoral Fins

Paired fins located on the sides of a fish's body, analogous to arms.

Pelvic Fins

Paired fins located lower on the body of a fish, analogous to legs.

Hagfish

Exclusively marine benthic scavengers with a skull but no spine, known for producing massive amounts of mucopolysaccharide slime as a defense mechanism.

Benthic

Describing organisms that live on, in, or near the seafloor or ocean floor.

Anadromous

A life cycle in which organisms spend most of their adult lives in the ocean and return to freshwater to spawn.

Micro Predator

An organism like a sea lamprey that briefly attaches to a larger host to feed on blood and body fluids before detaching.

Ossified Cartilage

Cartilage that is rigid and structured due to high concentrations of calcium, found in sharks and rays without forming true bone.

Placoid Scale

A specialized scale type found on sharks and rays with backward-pointing hook projections, creating a surface that feels smooth head-to-tail and like sandpaper in reverse.

Spiracle

Respiratory openings behind the eyes of certain cartilaginous fish that allow them to draw in water for breathing while resting on the seafloor.

Claspers

External organs found on male sharks and rays used for internal fertilization during copulation.

Heterocercal Tail

A caudal fin design where the top lobe is larger and longer than the bottom lobe.

Oviparous

A mode of reproduction where females lay egg cases (such as a mermaid's purse) into the environment to hatch externally.

Ovoviviparous

A reproductive strategy where eggs hatch inside the female reproductive tract, giving the impression of live birth without direct maternal nutrient transfer.

Viviparous

A mode of live birth where offspring develop internally and receive direct nutrition and oxygen from the mother.

Embryophagy

Also known as intrauterine cannibalism; a phenomenon in sand tiger sharks where the first hatched embryo inside the female consumes the remaining eggs and embryos.

Skates

Bottom-dwelling cartilaginous fish similar to rays that lack a tail spine and exclusively lay egg cases.

Holocephali

The group containing ratfish, characterized by deep-water bottom-dwelling habits, heterocercal tails, and all bones of the cranium being completely fused together.

Sarcopterygii

The group of lobe-finned fish, including coelacanths and lungfish, that represent the evolutionary lineage leading to tetrapods and amphibians.

Homocercal Tail

A caudal fin design typical of most bony fish where the upper and lower lobes are symmetrical and equal in size.

Operculum

A protective bony flap or plate that covers and guards the delicate gills in bony fish.

Swim Bladder

An internal gas-filled organ located near a bony fish's center of mass that regulates buoyancy without requiring swimming energy.

Lateral Line

A sensory system of pores running along the sides of a fish that senses pressure changes and vibrations in the surrounding water.

Countershading

A camouflage pattern where the dorsal side of a fish is dark and the ventral side is light, blending in with deeper water from above and bright water from below.

Disruptive Coloration

A color pattern featuring random stripes or bars that break up the silhouette of a fish to confuse predators about its orientation.

Cryptic Coloration

Camouflage coloration and texture that allow a fish to blend directly into its surrounding habitat, such as coral, sponges, or substrate.

Warning Coloration

Conspicuous and bright coloration that advertises to potential predators that an organism is toxic, venomous, or unpalatable.

Myomeres

Blocks of skeletal muscle tissue along a fish's body that contract in sequence to generate characteristic S-shaped swimming motions.