Lophophorates & echinoderms Flashcards
Invertebrates 3
Where do lophophorates fit?
Some are enterocoelous (=deueterstomes)
Some are schizocoelous (=protostomes)
Don’t comfortably fit in either group
rRNA sequences place them in protostomes
What is a lophophore?
A crown of hollow ciliated tentacles used for feeding
What are lophophorates?
Sessile suspension feeders enclosed in a secreted exoskeleton
Some are colonial
What are the 4 lophophorates?
Brachiopoda
Bryozoa
Phoronida
Rhabdopleura
What are the 2 types of Brachiopoda?
Articulate
= little peg in 1 side of shell & groove in the other –> forms a hinge
Inarticulate
= 2 halves don’t have a hinge
- muscle pulls them together
What are the features of Bryozoa?
Colonial
Individual zooids secrete a ‘house’ & multiply asexually
Members of colony connected by funicular cords - can exchange nutrients
Can move their lophophores
U-shaped gut
How do Bryozoa move their lophophores?
What does this result in?
- Lophophope extends
- ” spreads
- ” rocks & rotates
- ” retracts
= produces own feeding currents
Why do orgs live in colonies rather than as big individuals?
As animal size increases –> metabolic rate per unit weight of tissue decreases
–> biomass accumulates at progressively slower rate
When colonial - can maintain high rate of growth
What are the advantages of being in a colony?
Growth accelerates w/ increasing colony size
Feeding, non-dividing zooid at centre contribute nutrients to active ones at periphery
What type of symmetry do Starfish have?
Pentaradial
Are Echinoderms protostomes or deuterostomes?
Deuterostomes
What type of symmetry do Echinoderms have?
Describe their skeleton
What are their 2 faces called?
What type of symmetry do their larvae have?
Secondarily radially symmetrical
Calcareous endoskeleton made by mesoderm
Oral & aboral
Bilaterally symmetrical
What does ‘echinoderm’ mean?
‘spiny skin’
Describe Echinodermata embryology
Radial cleavage
Endodermally derived mesoderm
Enterocoely
Mouth not derived from blastopore (anus is)
How do sea stars eat?
Evert part of stomach over prey, secrete enzymes & absorb partially digested ‘soup’
Describe the different systems in Echinoderms
No excretory organs & no specialist organs for gas exchange
Circulatory system = heal system derived from coelomic cavities & sinuses
Nervous system = decentralised - nerve net + nerve ring + radial nerves
What is the water vascular system in Echinoderms?
Describe WVS fluid
Complex series of fluid-filled canals derived from coelom
–> services numerous tube feet
Similar to seat water w/ some protein, cells & high conc of K
Are Echinoderms dioecious or monoecious?
Dioecious
= separate sexes
Via which body part is water sucked into the WVS?
Madreporite
sieve plate stops grit getting into animal
How do Starfish move?
Muscles squeeze fluid into tube foot
- –> tube feet work in concert
- –> sucker on end of tube foot
What does mutable connective tissue do?
How does it do this?
Allows rapid & reversible changes in stiffness
–> means muscle tone can be altered w/out expending energy to contract muscles
Ionic movements alter weak interaction between macromolecules
–> Change in viscosity of collagen fibres
What are Asteroids?
Starfish
Free-living Echinoderms w/ radial symmetry & move not their oral surface
What can mutable connective tissue allow Asteroids to do?
Shed extremity & regenerate arms
What are the 5 classes within Echinodermata?
Crinoidea Asteroidea Ophiuroidea Echinoidea Holothuroidea
Give examples of Crinoidea
How do they feed?
Sea lilies & feather stars
Suspension feeders
Give examples of Asteroidea
How do they feed?
Sea stars
Opportunistic scavengers & predators
Give examples of Ophiuroidea
How do they feed?
Brittle stars & Basket stars
Predation, deposit feeding, scavenging or suspension feeding
or more than 1
Give examples of Echinoidea
How do they feed?
Sand dollars & Sea urchins
Herbivory, suspension feeding, detrivitory or predation
Give examples of Holothuroidea
How do they feed?
Sea cucumbers
Suspension or deposit feeders
