Animal biodiversity 4 Flashcards
(23 cards)
what is the sister group of the protostomes?
deuterostomes
what are the 2 groups within the deuterostomes?
1) echinodermata
2) chordata
in deuterostomes which forms first the mouth or anus?
the anus forms first then the mouth
what species does echinodermata include?
starfish and sea urchins
what symmetry do echinodermata have?
secondary radial and larvae bilateral
describe echinodermata vascular system
has digestive, reproductive and water vascular systems- WVS derived from coelom
what is the notochord and where is it found?
Longitudinal flexible rod located between digestive tract and nerve cord in embryo providing skeletal support in chordates
what is the second chord found in chordates?
dorsal hollow nerve chord
how do chordata feed?
through pharyngeal slits by filter feeding
what is a difference between chordata and protostomes?
chordata don’t usually end in an anus they have a muscular post anal tail
what is the function of the WVS in echinodermata?
branch into extensions called tube feet which function in locomotion, feeding and gas exchange
how do starfish class asteroidea feed and on what?
preys on molluscs, uses arms to pry open shell, everts stomach
what is a feature of brittle stars Class Ophiuroidea?
distinct central disc, long highly mobile arms
how do sea urchins Class Echinoidea move?
no arms they have rows of tube feet that move slowly
how do sea lilies Class Crinoidea feed?
long flexible arms used in suspension feeding
describe the structure of sea cucumbers Class Holothuroidea
they lack spines and have reduced endoskeleton - tube feet adapted as tentacles for feeding
describe the adult and larvae stages of sea squirts
adult - sessile filter feeder
larvae - free living with chordate characteristics
what are features of the Subphylum Cephalochordata (lancelets)
- no real head, brain, sensory organs, heart or jaws
- mouth surrounded by oral hood with cirri that strain and direct food to mouth.
describe segementation in chordates
muscle segments develop from blocks of mesoderm called somites arranged along the notochord
what are segmented muscle blocks called
Segmented muscle blocks are called myotomes
what is the simplest explanation for how segmentation evolved?
occurred 3 times separately in 3 groups
how is it thought vertebrates evolved?
from the larval form of a sessile ancestor by paedogenesis (sexual maturity in the larva), because of the similarity of cephalochordates to urochordate larval form
what are the 4 main characteristics of the subphylum verterbrata?
1) neural crest cells from embryonic ectoderm layer give rise to branches teeth and nervous system
2) cephalisation and brain derived from end of nerve chord
3) vertebral column (backbone) forming main body axis
4) closed circulatory system with chambered heart
