Jointed Appendages and Embryology Research

Websites:

http://www.cartage.org.lb/en/themes/sciences/zoology/animalclassification/Polygenetic/phylogenetictree/phylogenetictree.htm
http://library.thinkquest.org/28751/review/animals/8.html
http://www.earthlife.net/inverts/mollusca.html

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