Kingdom Animalia (Part 2) – Deuterostomes, Chordates & Vertebrate Diversity

Vocabulary flashcards covering major taxa, anatomical features, and key concepts from the lecture on deuterostomes, chordates, and vertebrate diversity.

Portuguese Man-O-War

A colonial cnidarian made of four genetically identical zooids, each specialized for floating, prey capture, digestion, or reproduction.

Deuterostome

A clade in which the embryo’s blastopore becomes the anus; includes echinoderms and chordates (humans are deuterostomes).

Phylum Brachiopoda

Lamp shells; marine lophophorates with bilateral symmetry, organs, three germ layers, and a tube-in-tube body plan.

Lamp Shell

Common name for brachiopods, Paleozoic marine animals with a dorsal and ventral shell and a U-shaped lophophore.

Lophophore

Ciliated, U-shaped ring of tentacles surrounding the mouth used for suspension feeding in lophophorate animals.

Phylum Echinodermata

Marine deuterostomes with adult radial symmetry, larval bilateral symmetry, water vascular system, tube feet, and calcareous ossicles.

Water Vascular System

Network of fluid-filled canals in echinoderms used for locomotion, feeding, respiration, and sensory perception.

Tube Feet

Hydraulic extensions of the water vascular system that aid echinoderms in movement, adhesion, and food handling.

Ossicles

Small calcareous plates forming the internal skeleton of echinoderms.

Nerve Ring (Echinoderms)

A simple circular nervous system encircling the mouth of echinoderms.

Madreporite

Porous entry plate for sea water into a sea star’s water vascular system.

Class Asteroidea

Sea stars; echinoderms with tube feet on suckers, ventral mouth, and high regenerative ability.

Class Ophiuroidea

Brittle stars; echinoderms with long flexible arms and tube feet lacking suckers.

Class Echinoidea

Sea urchins (regular echinoids) and sand dollars (irregular echinoids); echinoderms with a rigid test and movable spines.

Class Holothuroidea

Sea cucumbers; echinoderms with five rows of tube feet and evisceration defense mechanism.

Evisceration

Self-expulsion of internal organs by sea cucumbers as a defensive strategy, followed by regeneration.

Class Crinoidea

Feather stars and sea lilies; the oldest, most primitive echinoderms with upward-facing mouths.

Phylum Hemichordata

Acorn (proboscis) worms; marine animals with pharyngeal gill slits and a dorsal nerve cord, displaying early chordate traits.

Acorn Worm

Hemichordate capable of regenerating any body part; possesses gill slits and dorsal nerve cord but is not a true chordate.

Phylum Chordata

Deuterostome phylum defined by a notochord, dorsal hollow nerve cord, pharyngeal gill slits, and a muscular post-anal tail.

Notochord

Flexible, supportive rod running dorsal to the gut in chordate embryos; replaced by vertebrae in most vertebrates.

Dorsal Hollow Nerve Cord

Tubular nerve cord located dorsal to the notochord; develops into the central nervous system.

Pharyngeal Gill Slits

Openings in the pharynx; function in filter feeding, respiration, or develop into other structures in vertebrates.

Post-Anal Tail

Muscular tail that extends beyond the anus, providing propulsion in many chordates.

Subphylum Urochordata

Tunicates/sea squirts; sessile adult filter feeders that retain only gill slits, whereas free-swimming larvae show all four chordate traits.

Tunicate

Urochordate with a sac-like body, mucus net feeding, and cellulose-like tunic covering.

Subphylum Cephalochordata

Lancelets (amphioxus); small marine filter feeders retaining all four chordate characteristics throughout life.

Lancelet (Amphioxus)

Blade-shaped cephalochordate demonstrating persistent notochord, dorsal nerve cord, gill slits, and post-anal tail.

Subphylum Craniata

Chordates possessing a skull; includes vertebrates where the notochord is replaced by a cartilaginous or bony vertebral column.

Neoteny (Paedomorphosis)

Retention of juvenile characteristics into adult life, seen in some salamanders and other vertebrates.

Class Myxini

Hagfish; jawless, slime-producing scavengers with cartilaginous skeletons and two-chambered hearts.

Hagfish Slime

Viscous defensive secretion produced by hagfish that clogs predator gills.

Class Cephalospidomorphi

Lampreys; jawless, parasitic fish with a stiff protein cartilage and rasping oral disk.

Lamprey

Jawless vertebrate that attaches to host fish and feeds on blood; exhibits seven external gill slits.

Class Placodermi

Extinct armored fishes of the Devonian Period, exemplified by Dunkleosteus.

Class Chondrichthyes

Cartilaginous fish (sharks, skates, rays) lacking swim bladders, possessing urea for osmoregulation and lateral line system.

Lateral Line System

Sensory organ in aquatic vertebrates that detects water vibrations and movement.

Oviparous

Reproductive mode where eggs are laid and hatch outside the mother’s body.

Ovoviviparous

Reproductive mode where eggs hatch inside the mother and young are then birthed live.

Class Osteichthyes

Bony fish with calcium-phosphate skeletons, opercula covering gills, swim bladders, and external fertilization.

Operculum

Bony flap that protects the gills and aids ventilation in bony fishes.

Swim Bladder

Gas-filled sac allowing bony fish to regulate buoyancy and maintain depth.

Subclass Sarcopterygii

Lobe-finned fishes with fleshy, limb-like fins; includes coelacanths and ancestors of tetrapods.

Coelacanth

Living sarcopterygian once thought extinct; rediscovered in 1938 (lecture notes mention 1997).

Subclass Actinopterygii

Ray-finned fishes with fins supported by bony rays; the largest vertebrate subclass.

Tetrapoda

Vertebrate grouping of four-limbed animals: amphibians, reptiles, birds, and mammals.

Class Amphibia

Ectothermic tetrapods with dual life cycles, moist skin gas exchange, metamorphosis, and three-chambered hearts.

Spermatophore

Gelatinous packet of sperm deposited by male amphibians for uptake by females.

Order Anura

Frogs and toads; tailless amphibians, frogs with smooth skin, toads with rough warty skin.

Order Urodela

Salamanders and newts; amphibians with tails throughout life.

Order Apoda

Caecilians; legless, burrowing amphibians resembling worms.

Class Reptilia

Ectothermic amniotes with keratinized scales, internal fertilization, and mostly three-chambered hearts (four in crocodilians).

Amniotic Egg

Egg with specialized membranes (amnion, chorion, yolk sac, allantois) enabling full terrestrial development.

Order Chelonia

Turtles and tortoises; reptiles with dorsal carapace and ventral plastron shells.

Order Rhychocephalia

Tuatara; sole surviving reptile order with a parietal 'third eye' on the head.

Tuatara

New Zealand lizard-like reptile representing an ancient lineage; possesses a light-sensitive parietal eye.

Order Squamata

Lizards and snakes; reptiles with kinetic skulls and, in snakes, limb reduction.

Poison vs. Venom

Poison is harmful when ingested/absorbed; venom is harmful when injected by a bite or sting.

Venomous Snake Traits

Stout body, triangular head, cat-like pupils, bright colors, and single row of scales past the cloaca.

Order Crocodilia

Crocodiles, alligators, caimans, and gavials; reptiles with four-chambered hearts and powerful jaws.

Class Aves

Endothermic reptiles (birds) with feathers, air-sac respiratory system, four-chambered hearts, and keeled sternums.

Keel (Bird)

Prominent extension of the bird sternum providing attachment for flight muscles.

Class Mammalia

Endothermic vertebrates with hair, mammary glands, diaphragm, differentiated teeth, and three middle-ear bones.

Monotremes

Egg-laying mammals such as the platypus and echidna.

Marsupials

Mammals that give birth to underdeveloped young which complete development in a pouch.

Placentals

Mammals whose embryos develop within a uterus nourished by a placenta.

Tooth Differentiation

Presence of incisors, canines, premolars, and molars, characteristic of mammals.