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
Echinoderms are all marine organisms: sea starts, brittle starts,
sea urchis, sand dollars and sea cucumbers
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 fivethis is secondarily adquired, larvae is bilateral
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 Asteroidea
Exercise 16A:
– Phylum: Echinodermata
• Clase Asteroidea- sea starts
• Asterias
External Anatomy
Clase Asteroidea
Exercise 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 Holothuroidea
Exercise 16D:
– Phylum: Echinodermata
• Clase Holothuroidea- sea cucumbers
• Cucumaria
External Anatomy
Clase Asteroidea
Exercise 16D:
– Phylum: Echinodermata
• Clase Holothuroidea- sea cucumbers
• Cucumaria
Internal Anatomy
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
Exercise 16B:
– Phylum: Echinodermata
• Clase Ophiuroidea- brittle starts
• Ver material preservado
External Anatomy
Class Echinoidea-sea urchis
Characteristics
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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
Exercise 16C:
– Phylum: Echinodermata
• Clase Echinoidea- sea urchis
• Ver material preservado
External Anatomy
Clase Echinoidea
Exercise 16C:
– Phylum: Echinodermata
• Clase Echinoidea- sea urchis
• Ver material preservado
External Anatomy
Larvaes
Bipinnaria
Brachiolaria