Ch 3 – The Vertebrate Story

Vertebral Column

A series of separate bones or cartilage blocks (vertebrae) joined as a backbone that defines the major body axis.

Cranium

A skull that encases or partially encases the brain.

Cephalization

The clustering of specialized sensory organs at the anterior end with an enlarged neural tube forming the brain (forebrain, midbrain, and hindbrain).

Prevertebrate

A suspension-feeding organism similar to a lancelet that developed a muscular pump to move water more efficiently than cilia alone.

Agnathan

A jawless vertebrate that used the muscular pump to produce a food-bearing current for suspension or deposit feeding (shoveling mud).

Gnathostome

A jawed vertebrate that transitioned to collecting food by predation using grasping jaws.

Ectothermic

Body temperature is regulated by the environment.

Aquatic

Live in water.

Fish Circulatory System

Possess a 2-chambered heart.

Fish Respiration

Most use gills for oxygen exchange.

Fish Integument

Most have scales (except for agnathans).

Pectoral Fin

The anterior pair of fins in gnathostomes.

Pelvic Fin

The posterior pair of fins in gnathostomes.

Spiracle

A small, rounded opening derived from the first gill slit, found in elasmobranchs.

Operculum

A protective covering over the gills; it is a bony plate in Osteichthyes but a skin flap in Holocephali (chimaeras).

Swim Bladder

A gas-filled sac that helps bony fish maintain buoyancy in water.

Heterocercal Tail

An asymmetrical tail where the upper lobe is larger (common in sharks).

Homocercal Tail

A symmetrical tail common in teleost fish.

Lepidotrichia

Slender bony rods or 'rays' that provide fanlike support to the fins of bony fishes.

Diphycercal Tail

A tail type found in Actinistia (coelacanths) where the vertebral column extends to the tip.

Chiridium

A muscular limb with well-defined joints and digits (dactylous).

Temporal Fenestra

Openings in the temporal region of the skull used to classify amniotes.

Temporal Arch/Bar

The bony spans that connect or bound the temporal fenestrae.

Carapace

The dorsal (top) part of a turtle shell, made of expanded ribs and skin plates.

Plastron

The ventral (bottom) part of a turtle shell made of fused bony pieces.

Anapsid

No temporal fenestrae.

Synapsid

A single temporal fenestra and bar.

Diapsid

Two temporal fenestrae and two bars.

Amphibians

'Double life' (water and land); lay anamniotic eggs; have mucus glands to keep skin moist; undergo metamorphosis; 3-chambered heart.

Reptiles

Ectothermic; dry, scaly skin; claws on toes; breathe with lungs; lay amniotic eggs; most have a 3-chambered heart (crocs have 4).

Birds (Aves)

Endothermic; 4-chambered heart; feathers (modified keratin scales); flight skeleton with thin, hollow, fused bones; keratinized beaks without teeth; lay amniotic eggs.

Mammals

Endothermic; 4-chambered heart; large brain-to-body ratio; have hair (pelage), mammary glands, sebaceous glands, and anucleate red blood cells.

Agnatha (Superclass)

Jawless; lack bone, scales, and paired fins; single nostril; cartilaginous endoskeleton.

Cyclostomes

Living agnathans including Hagfishes (Myxini) and Lampreys (Petromyzontida).

Gnathostomes

Jawed vertebrates with paired fins.

Chondrichthyes

"Cartilage fish" with placoid scales; includes Elasmobranchii (sharks, rays) and Holocephali (chimaeras).

Osteichthyes

"Bony fish" with an ossified endoskeleton and swim bladder.

Actinopterygii

Ray-finned fishes supported by lepidotrichia.

Teleostei

Largest group of ray-finned fish; homocercal tail; circular scales.

Sarcopterygii

"Fleshy-finned" or lobe-finned fishes; ancestors of terrestrial vertebrates; includes Actinistia (coelacanths) and Dipnoi (lungfishes).

Tetrapoda

Organisms with a chiridium (muscular limb with digits).

Testudinata

Turtles; anapsid skull; carapace and plastron.

Lepidosauria

Snakes, lizards, and tuatara.

Mammalia

Class of animals that includes monotremes, metatherians, and eutherians.

Monotremata

Egg-laying mammals; lack nipples (sweat milk); e.g., Platypus, Echidna.

Metatheria

Marsupials; give birth to underdeveloped young that develop in a pouch; e.g., Kangaroos.

Eutheria

Placental mammals.