LABORATORIO

Phylum Echinodermata

EJERCICIO 16

Goals for today• Learn to recognized the Phylum

Echinodermata from other animals• Learn the main ‘diagnostic’ characteristics of

the group.• Learn about some species biology

Phylum Echinodermata

Key characteristics of the Phylum:•Abandoned bilateral symmetry to become radial (just larvae is bilateral)•Deuterostomates (as Hemichordata and Chordata)•Dermal endoskeleton of calcareous plates and spines often fused like an armor•Water-vascular system that powers tiny tube feet for locomotion and food gathering•Pedicellariae (pincerlike structures)•Dermal branchiae (skin gills)•Lack a defined head: nervous and sensorial system poorly develop•Pentaradial symmetry: five o multiples of five- this is secondarily adquired, larvae is bilateral

Echinoderms are all marine organisms: sea starts, brittle starts, sea urchis, sand dollars and sea cucumbers

Class Asteroidea-Sea starts

Characteristics

• Body star-shaped with 5 or more arms• Arms relatively thick; not distinct from

central body disk• Tube feet lie in open ambulacral

grooves• Gonads and digestive tract extend into

arms• Madreporite (opening to water

vascular system) and anus aboral• Mostly slow-moving predators

Clase AsteroideaExercise 16A: – Phylum: Echinodermata

• Clase Asteroidea- sea starts• Asterias

External Anatomy

Clase AsteroideaExercise 16A: – Phylum: Echinodermata

• Clase Asteroidea- sea starts• Asterias

Internal Anatomy

Class Holothuroidea-Sea cucumbers

Characteristics

• Body elongated in oral-aboral axis• Secondarily bilaterally symmetric

(no dorsal tube feet)• Skeleton reduced to isolated

ossicles; soft-bodied• Ring of tentacles around mouth• Most are deposit feeders in soft

sediments

Clase HolothuroideaExercise 16D: – Phylum: Echinodermata

• Clase Holothuroidea- sea cucumbers• Cucumaria

External Anatomy

Clase Asteroidea

Internal Anatomy

Exercise 16D: – Phylum: Echinodermata

• Clase Holothuroidea- sea cucumbers• Cucumaria

Class Ophiuroidea-Brittle starts

Characteristics

• Five arms articulated; distinct from body disk• Arms may be branched (basket stars) or

unbranched (brittle stars)• Arms lack open ambulacral groove• Lack anus• Most are deposit or suspension feeders

Clase Ophiuroidea

External Anatomy

Exercise 16B: – Phylum: Echinodermata

• Clase Ophiuroidea- brittle starts• Ver material preservado

Class Echinoidea-sea urchis

Characteristics

• Body globular or disk-shaped; lack arms• Skeletal plates fused into rigid test• Pores in test allow tube feet to exit• Spines moveable• Protrusible jaw apparatus (Aristotle's Lantern)• Mostly herbivores or detritivores, but some predatory

Clase Echinoidea

External Anatomy

Exercise 16C: – Phylum: Echinodermata

• Clase Echinoidea- sea urchis• Ver material preservado

Clase Echinoidea

External Anatomy

Exercise 16C: – Phylum: Echinodermata

• Clase Echinoidea- sea urchis• Ver material preservado

Larvaes

BrachiolariaBipinnaria