Survey of the Animal Kingdom – Phyla Echinodermata & Chordata

Vocabulary flashcards covering core terms, structures, classes, and evolutionary concepts from the lecture on echinoderms and chordates, including embryological development, anatomy, and major taxonomic groups.

Deuterostome

Animal whose embryonic development features radial, indeterminate cleavage and formation of the anus from the blastopore.

Protostome

Animal whose embryonic development features spiral, determinate cleavage and formation of the mouth from the blastopore.

Radial Cleavage

Early embryo divisions in which new cells are stacked directly above previous cells; characteristic of deuterostomes.

Spiral Cleavage

Early embryo divisions in which new cells form at oblique angles; characteristic of protostomes.

Indeterminate Cleavage

Each early embryo cell retains the capacity to develop into a complete organism; typical of deuterostomes.

Determinate Cleavage

Each early embryo cell’s fate is fixed; typical of protostomes.

Blastopore

First embryonic opening; becomes the anus in deuterostomes and the mouth in protostomes.

Phylum Echinodermata

Marine deuterostomes with pentaradial adult symmetry, endoskeleton of calcium ossicles, and a water vascular system.

Pentaradial Symmetry

Body plan based on five-part radial arrangement seen in adult echinoderms.

Ossicles

Calcium carbonate plates that form the internal skeleton of echinoderms.

Water Vascular System

Network of fluid-filled canals in echinoderms used for locomotion, feeding, and gas exchange.

Tube Feet

Hydraulic extensions of the water vascular system ending in suction disks; used for movement and prey handling.

Madreporite

Porous entry plate that admits seawater into the water vascular system of echinoderms.

Pedicellariae

Tiny pincer-like structures on sea stars used for cleaning and defense.

Dermal Gills

Skin extensions on sea stars that provide gas exchange and excretion.

Aristotle’s Lantern

Jaw-like chewing apparatus of sea urchins composed of five calcium plates and muscles.

Class Asteroidea

Sea stars; possess broad arms continuous with the central disc and obvious tube feet in open grooves.

Bipinnaria Larva

Free-swimming, bilaterally symmetrical larval stage of sea stars.

Class Ophiuroidea

Brittle stars; have slender, highly flexible arms and reduced tube feet used mainly for sensory functions.

Class Crinoidea

Sea lilies & feather stars; stalked or free-swimming echinoderms with upward-facing mouth and filter-feeding arms.

Class Echinoidea

Sea urchins & sand dollars; globe- or disc-shaped echinoderms with fused ossicles forming a rigid test and no arms.

Class Holothuroidea

Sea cucumbers; elongated echinoderms with reduced ossicles, leathery body, and tentacles around the mouth.

Phylum Chordata

Deuterostome animals that, at some life stage, possess a notochord, dorsal hollow nerve cord, pharyngeal slits, and post-anal tail.

Notochord

Flexible rod that runs lengthwise in chordate embryos, providing support; replaced by vertebral column in vertebrates.

Dorsal Hollow Nerve Cord

Tube of nervous tissue above the notochord; develops into the central nervous system.

Pharyngeal Slits

Openings in the pharynx used in filter feeding, gas exchange, or modified into other structures in vertebrates.

Post-anal Tail

Muscular tail that extends beyond the anus in chordate embryos; retained or reduced in adults.

Subphylum Urochordata

Tunicates or sea squirts; adults are sessile filter feeders, larvae possess all four chordate traits.

Subphylum Cephalochordata

Lancelets; small, fish-like marine animals retaining chordate features throughout life.

Subphylum Vertebrata

Chordates with vertebrae surrounding the spinal cord; includes fishes, amphibians, reptiles, birds, and mammals.

Ammocoete

Larval stage of lampreys resembling lancelets in body plan and feeding strategy.

Lateral Line System

Series of sensory canals along fish skin that detect water movements and vibrations.

Operculum

Bony flap covering and protecting the gills in bony fishes; aids in ventilating gills while stationary.

Swim (Air) Bladder

Gas-filled sac in most bony fishes that provides buoyancy control.

Amniotic Egg

Watertight egg with amnion, chorion, allantois, and yolk sac; key adaptation for terrestrial vertebrates.

Poikilotherm

Animal whose internal body temperature varies with environmental temperature (e.g., reptiles, amphibians, fishes).

Homeotherm

Animal that maintains a constant internal body temperature (e.g., birds, mammals).

Archaeopteryx

Jurassic fossil showing both reptilian and avian features; transitional form between dinosaurs and birds.

Tiktaalik

Late Devonian lobe-finned fish exhibiting both fish and tetrapod traits; important in study of vertebrate land invasion.

Class Agnatha

Jawless fishes (lampreys & hagfishes) lacking paired fins and true vertebral centra.

Class Chondrichthyes

Cartilaginous fishes (sharks, rays, skates) with skeleton of cartilage, placoid scales, and exposed gill slits.

Class Osteichthyes

Bony fishes; possess ossified skeleton, operculum, and swim bladder; includes ray-finned and lobe-finned species.

Class Amphibia

Frogs, salamanders, caecilians; first tetrapods, with moist skin and dual life in water and on land.

Class Reptilia

Turtles, snakes, lizards, crocodilians; amniotes with keratinized scales and primarily terrestrial reproduction.

Class Aves

Birds; feathered, homeothermic vertebrates with wings, hollow bones, and high metabolic rate.

Class Mammalia

Hair-bearing, milk-producing vertebrates with differentiated teeth and endothermy.

Mammary Glands

Specialized skin glands in mammals that secrete milk to nourish young.

Pedicellaria

See Pedicellariae; minute pincer structures on sea stars used for cleaning and defense (singular form).