Websites:
How Invertebrates Move:
- Annelida (earth worms, leeches, marine worms) have segmented bodies and simple appendages, move by their various muscles and their appendages,
- Mollusca (squid, snails, slugs) glide by using cillia or ventral muscular waves
- Arthropoda (crab, shrimp lobster) move by their jointed appendages, exoskeleton and segmented bodies)
- Echindoermata (starfish, sea urchins, etc.) move by using suckered "tube feet" or nudging themselves across the bottom of the ocean floor
- Cnideria (jellyfish)Platyhelminthes (flat worms) and Nemotoda (round worms) move by gliding using cilia and swimming (pulse rhythmically-pulling it forwards
Embryology:
Embryology:
Chordata:
Echidermata:
Arthropoda:
Mollusca:
Annelida:
Nemotoda:
Platyhelminthes:
Cnideria:
http://planet.uwc.ac.za/nisl/biodiversity/loe/page_13.htm
· Reproduce by releasing eggs and sperm into the sea
· Fertilized egg develops into free swimming creature
· Settles at the bottom of the sea
· Develops into tiny flower-like organism (called polyp)
· Polyp bud in a different – produce medusa- detach themselves and are free swimming again
Development Stage:
http://www.wisegeek.com/what-is-the-blastula.htm
Zygote (fertilized egg)) divides (process called cleavage), these first divisions creates a solid ball of cells called morula
Blastula then forms when dividing cells create a layer called blastoderm that surrounds the central cavity (this transition from the morula to the blastula is called blastulation
Gastrulation is the next embryonic structure (gastrula)
Blastula: early stage of an embryo by the division of an ovum (liquid-filled sphere whose wall is made of a single layer of cells), implantation in the wall of the uterus occurs