Invertebrate chordates "Diversity" (Amphioxus"lancelet:…
Invertebrate chordates "Diversity"
Amphioxus"lancelet: Nahla Aljeraisy
Similarities and differences: They are similar in having the four structures which is notochord, pharyngeal pouches, postainal tail and dorsal tubular nerve cord. And they are different in not having head, eyes or sendory organs.
Nervous system: consist of main branching nerves and a simple brain at the anterior end of the animal.
Movement: The arrangement of segmented muscle is similar to that in in vertebrates enabling lancelet to swim with a fishlike motion.
Circulatory system: Blood passes through the body by the action of pumping blood vessels, as there is no true heart
Feeding and digestion: They are filter feeders, get food water enters the mouth of the lancelet and pass through the phyrangial gills. Food is trapped and passed on to a stomach structure to be digested.
Reproduction: Lancelet have separate sexes, and fertilization is external.
color: lancelet lack color in their skin, which is only cell layer deep.
Tunicate "Sea squirt" By Sara Alrowaidan
1) Naming reason:
They are named based on their thick outer coverings "Tunic", that covers their small, sac like bodies.
They are named sea squirt because they eject stream of water with the force of excurrent siphon
2) Similarities and differences with vertebrates chordates:
a) Similarities: they have all characteristics as larvae "Postanal tail, pharyngeal pouches, notochord, and dorsal tubular nerve cord"
b) Differences: They loose all characteristics as adults, except for pharyngeal pouches and they become sessile.
3) Feeding and digestion:
a) Water is drawn into the sac like bodies through the incurrent siphon.
b) Food particles are trapped in a mucous and moved to the stomach.
c) Digestion takes place in stomach
Circulation of the body is preformed by heart and vessels.
5) Nervous system:
Consist of main nerve complex and branching neurons
They are hermaphrodites, reproduce by external fertilization