Echinoderms and Chordates Lecture Notes

Flashcards about echinoderms and chordates

Echinoderms

Invertebrates with durastome development, coelomae, and adult radial symmetry but bilateral larvae.

Echinoderm skeleton

Internal skeleton covered by a thin skin.

Water vascular system

System that props up internal structures with water.

Asteroidia

Sea stars, have arms that radiate from a central disc.

Ophoridia

Brittle stars, have a distinct central disc and flexible arms for movement.

Echinoidia

Sea urchins and sand dollars.

Holothuroidea

Sea cucumbers, have bilateral symmetry and reduced skeletons.

Neural cord

Primitive structure that develops into the skeleton.

Nerve cord

Structure that evolves into the brain and spinal cord.

Pharyngeal slits

Slits used for feeding in primitive chordates and respiration in fish.

Post anal tail

Used for balancing in terrestrial animals and propulsion in aquatic animals.

Urochordata

Subphylum of chordates with tunicates where chordate characteristics are only in the larval stage.

Cephalochordata

Subphylum of chordates with lancelets where chordate characteristics are in both young and adults.

Craniates

Animals with a head region, skull, brain, eyes, and sensory organs.

Haikouella and Haikouichthys

Early chordates.

Hagfish

Have a head. Skull is made of cartilage

Hagfish defense

Have slime to protect themselves and are scavengers.

Lamprey

Primitive vertebrae, no jaws, ectoparasites.

Evolution of jaws

Jaws evolved from structures supporting gill slits

Gnathostomes

Enhance sensory system, mineralized endoskeleton

Chondrichthyes

Sharks, rays, and skates with cartilage skeletons and no rib cage.

Rays

Live birth, kite-like shape, a long flexible tail with spines. Flaps its side like a bird.

Skates

Lays eggs, short and fatter tail with fins. Swims with a wave like motion.

Shark fins

Pectoral fins are used for lifting. Pelvic dorsal, anal fins used to keep the shark stabilized. Caudal fin is used for propulsion.