Echinoderms Flashcards
What are phylum Echinodermata united by?
Presence of a water vascular system
What is the age range of phylum Echinodermata?
Cambrian to recent
What is the Stereom?
Mesodermal calcitic skeleton
(middle layer of cells)
What is the symmetry of Enchinodermata?
Typically 5 fold Pentameral symmetry
Besides pentameral symmetry what other symmetry might be present in Echinodermata?
Superimposed bilateral symmetry
What is the diversity of echinodermata like?
Diverse group with wide variety of exclusively marine ecological niches
What 2 subphylum can Echinodermata be divided into?
Pelmatozoa
Eleutherozoa
What are some examples of Subphylum Eleutherozoa?
Holothurians (sea cucumbers)
Asteroid starfish
Ophioroids (brittle stars)
What are some examples of echinoidea from Subphylum Eleutherozoa
Sea urchins and Sand dollars
What is the upper view of an echinoidea called?
Aboral
What main central feature of Echinoidea can be seen in aboral view?
Apical disc
What is the apical disc?
Area which contains the periproct (anus)
What is the periproct surrounded by?
5 plates with large pores (gonopores)
What makes one plate surrounding the periproct different?
Madreporite which is a different colour - imporant for water filtering
How is the pentameral symmetry of regular echinoidea defined?
10 pairs of ambulacrum plates
What are ambulacral plates?
penetrated pores through which tube feet emerge
What are interambulacral plates?
Where there are no pores in aboral view
What is the function of tubercles?
the channel water flow and act as basal support for the spines
What are the 2 general sizes/ function of spines on echinoidea?
long spines for protection
short spines for locomotion
What is the name of the lower view of echinoidea?
adoral
What can be viewed in the centre of a regular echinoidea in adoral view?
Peristome - mouth
What can also be seen in adoral view of a regular echinoidea besides the peristome?
Aristotle’s lantern
Perignathic girdle