Echinoids Flashcards
What is their phylum and types and class
Echinodermata
Regular and irregular
Echinoidea
What is a regular echinoids symmetry
What is a irregular echinoids symmetry
Five-fold symmetry
Bilateral
What is their soft tissue body part called
Tube feet
What is the skeleton called and what shape is it
Test
Hemisphere
What does it consist many of and what are they made out of
Many interlocking plates
Calcite
What are the two types of plates called
Ambulacra
Interambulacra
How many plates are in total and how many of each
10
5
Which plate is narrower
Ambulacra
How many rows of plates do the ambulacra consist of and what are they perforated by
2
Pore pairs
In real life what would pore pairs have
Tube feet
What do interambulacra plates have on their surface
Tubercles
In real life what would tubercles have attached on them
Spines
What view is where the anus if facing up
Aboral
What view is where the mouth is facing up
Oral
What is the madreporite
Genital plate for taking in water for the water vascular system
What were the tube feet used for
Respiration
Movement
Attachment
Where is the apical system
In the centre of the upper or aboral surface
The apical system consists of what
Ten plates arranged in two rings around a centre anus
How many genital plates are there and what is the largest
5
Madreporite
How does the madreporite work
It is perforated by many tiny pores allowing water to enter the animals water vascular system
In-between the large plates are what
Smaler genital plates
What is the anus surrounded by and what does it release
A membrane called the periproct
Waste, legs and sperm
What is the mouth surrounded by
A membrane called the peristome
How are the edges of the test shaped and what does this produce
They are turned inwards producing a lip
What is this lip called
The perignathic girdle
What is the structure of the feeding apparatus and what is it called
There are five jaws, each with a sharp tooth supported inside the mouth called Aristotle’s lantern
What do the tubercles consist of
The boss (a wide base) the mamelon (a nipple like structure in the centre of the boss)
How are the spines attached
Muscles attach the spine to the boss and the muscles contract to move the spines in a chosen direction
What is the mode of life for regular echinoids
Live on rocky shores
High-energy environment
Feed on algae by scrapping it off rocks
How are irregular echinoids characterised
By having the anus outside of the apical system
The anus has moved towards the edge of the test
Named examples of irregular echinoids
Micraster
Sad dollar
What does the mouth lack (Irregular)
Jaws and the perignathic girdle
How does it feed (Irregular)
It takes in particles of water and filters these
What is the labrum, where is it and what does it do
Large lip
On the lower side of the mouth
Used to direct the currents and prevent unwanted sediments getting into the mouth
What is behind the labrum and what does it form
A modified set of interambulacra plates
Plastron
What does the plastron have and do
Tubercles for attachement of spines
The spines are used to help dig a burrow or to move within it
What is the ambulacra called on irregular echinoids
Petaloid ambulacra
What do the petaloid ambulacra at the anterior end of the animal form
They are bigger
Form the anterior groove
What is the anterior groove lined with and what do they do and what is it called
Lined with cilia
Beat to create a current to pass food particles to the mouth
Called the fasciole
What is the modified area close to the anus called (Irregular)
Sub-anal fasciole
What does the sub-anal fasciole do
Many beating cilia to take waste particles and direct them into the sanitary tube
How are the tube feet on the two posterior ambulacra modified
To keep the burrow clean and maintain the sanitary tube
What is their mode of life (Irregular)
Live in soft sediment
Low-energy environment (infaunal)
Filter feeder
