echinoderm lab

Environment of echinoderms

All marine environments

Body plan of echinoderms

Coelomate deuterostomes with reduced cephalization (as adults)

Digestive system of echinoderms

Complete digestive system

Echinoderm development symmetry

Bilateral larvae develop into pentaradial adults

Echinoderm nervous system

Nerve ring with radial nerves; no brain

Echinoderm endoskeleton

Calcareous plates, spines, and ossicles

Water vascular system function

Locomotion, feeding, gas exchange, and waste removal

Special ability of echinoderms

Regeneration

Mutable connective tissue

Tissue that can harden or soften

Meaning of echinoderm

"Spiny-skinned"

Sea urchin characteristics

Movable spines and round body

Function of sea urchin spines

Defense and burrowing

Sea urchin diet

Algae (herbivore)

Sand dollar structure

Flattened body with short spines

Sand dollar diet

Detritus

Sea cucumber structure

Soft, elongated body with reduced endoskeleton

Sea cucumber locomotion

Tube feet

Sea cucumber feeding structures

Oral tentacles

Evisceration

Defense mechanism where organs are expelled

Sea star body structure

Five arms from a central disk

Sea star oral side

Mouth and tube feet

Sea star aboral side

Anus and madreporite

Sea star reproduction

Dioecious

Sea star feeding

Evert stomach into bivalves

Chordate symmetry

Bilateral symmetry

Chordate body plan

Coelomate deuterostomes

Chordate circulatory system

Closed circulatory system

Metamerism

Body segmentation

Big 4 chordate traits

Notochord; pharyngeal slits; dorsal hollow nerve cord; post-anal tail

Urochordata (tunicates) Big 4

Present only in larval stage

Adult tunicate traits

Retain pharyngeal slits only

Tunicate feeding

Filter feeding

Cephalochordata (lancelets) Big 4

Present in adults

Lancelet feeding

Marine filter feeders

Characteristics of phylum Echinodermata

Marine; coelomate deuterostomes; pentaradial adults; bilateral larvae; complete digestive system; endoskeleton of calcareous plates; water vascular system; nerve ring (no brain); regeneration; mutable connective tissue

Larval vs adult echinoderm symmetry

Larvae are bilateral; adults are pentaradial

Functions of water vascular system

Locomotion; feeding; gas exchange; waste removal

Sea urchin characteristics

Round body; long movable spines; herbivorous; feed on algae; spines for defense and burrowing

Sand dollar characteristics

Flattened body; short spines; tube feet; detritus feeders

Sea cucumber characteristics

Elongated soft body; reduced endoskeleton; tube feet; oral tentacles for feeding

Sea star characteristics

Five arms; central disk; tube feet; carnivorous; evert stomach to digest prey

Sea cucumber defense

Evisceration (expelling internal organs)

Sea star oral side

Mouth and tube feet; used for feeding and movement

Sea star aboral side

Anus and madreporite; water entry into system

Madreporite

Opening that allows water into the water vascular system

Tube feet

Movement, feeding, and gas exchange

Radial canal

Distributes water to tube feet in each arm

Ampulla

Bulb that controls tube feet movement

Path of water vascular system

Madreporite → stone canal → ring canal → radial canals → tube feet

Identify echinoderms

Sea stars, sea urchins, sand dollars, sea cucumbers (by shape and structure)

Characteristics of phylum Chordata

Bilateral; coelomate deuterostomes; closed circulatory system; complete digestive system; metamerism; possess “Big 4”

Big 4 chordate characteristics

Notochord; pharyngeal slits; dorsal hollow nerve cord; post-anal tail

Notochord function

Support and flexibility

Pharyngeal slits function

Filter feeding or gas exchange

Dorsal hollow nerve cord function

Develops into central nervous system

Post-anal tail function

Movement and balance

Subphyla of chordates

Urochordata; Cephalochordata; Craniata

Larval vs adult sea squirt

Larvae have all Big 4; adults retain only pharyngeal slits

Lancelet feeding

Filter feeding using pharyngeal slits

Lancelet external anatomy

Mouth with oral tentacles; dorsal fin; muscle segments; atriopore

Oral tentacles

Prevent large particles from entering mouth

Atriopore

Exit opening for water

Lancelet internal anatomy

Notochord; dorsal nerve cord; pharyngeal slits; intestine; anus; post-anal tail

Pharyngeal slits in lancelet

Filter food from water

Hepatic cecum

Digestion and enzyme secretion

Identify urochordates and cephalochordates

Tunicates (sea squirts) and lancelets by body shape and features

Urochordate characteristics

Larval Big 4 only; adult reduced; filter feeders; sac-like body

Cephalochordate characteristics

Retain Big 4 as adults; elongated body; filter feeders