Vertebrate Zoology Chapter 6: Origin and Radiation of the Chondrichthyes

This set of flashcards covers key vocabulary, terms, and definitions from Chapter 6 of Vertebrate Zoology, focusing on the origin and classification of Chondrichthyes.

Acanthodii

An extinct group of fish known as 'spiny sharks', characterized by spines anterior to each fin.

Chondrichthyes

Class of cartilaginous fishes including sharks and rays, with a skeletal structure made primarily of cartilage.

Placoid scales

Tooth-like scales found on the skin of sharks and rays, derived from the body armor of placoderms.

Claspers

Reproductive structures found on the pectoral fins of male sharks, used for internal fertilization.

Heterocercal tail

A type of tail fin found in sharks where the upper lobe is longer than the lower lobe, aiding in propulsion.

Viviparous

Reproductive mode where the young are born alive and nourished directly by the mother.

Oviparous

Reproductive mode in which eggs are laid and develop outside the mother’s body.

Ovoviviparous

Reproductive strategy in which eggs hatch inside the mother's body and the young are born live.

Euselachii

Subclass of chondrichthyans that includes all modern sharks and rays.

Neoselachii

Subdivision of Euselachii that encompasses all extant sharks.

Calcified cartilage

A tissue found in sharks that provides strength equivalent to bone, while remaining lightweight.

Denticles

Tiny tooth-like structures covering the skin of sharks, contributing to their hydrodynamic efficiency.

Ampullae of Lorenzini

Specialized sensory organs in sharks that detect electrical fields in the water.

Cranial kinesis

The ability of sharks to move their upper jaw independently of the skull, enhancing feeding capabilities.

Dorsoventrally flattened

Describes the body shape of rays and skates, allowing for adaptation to a bottom-dwelling lifestyle.

Megalodon

An extinct species of shark recognized as one of the largest predators in history, existing approximately from 28 to 1.5 million years ago.

Biofluorescence

The ability of an organism to absorb light and then re-emit it at a different wavelength, often seen in certain shark species.

Chemoreception

The sense of smell in sharks, allowing detection of prey from significant distances.

Bioluminescence

The production and emission of light by living organisms, which can be used as a predatory or defensive mechanism.