characteristics of echinodermata (5)

- spiny skin - internal skeleton - five-part body - water vascular system - tube feet

external features of starfish oral side

oral - mouth mouth in centre ambulacral runs from mouth to tip of each arm grooves bordered by tube feet (podia)

external features of starfish aboral side

aboral - a - ass anus barely visible eyespots at tip of arms madreporite is a calcareous sieve leading to interval water vascular system

internal structure of starfish from aboral side

water vascular system is important for locomotion, feeding, waste transport & gas exchange.

external structure of sea urchin

oral - mouth (bottom side) aboral - a - anus (top side)

internal structure of sea urchin

structure & function of aristotles lantern

chewing apparatus. highly mobile. 5 teeth that meet at mouth opening