Body Symmetry & Coelomate. Symmetrical. Acoelomate no mesoderm. Pseudocoelomate mesoderm attach to one side but no cleavage. Coelomate mesoderm cleavage with coelom inbetween. Segmented Body. Porifera (spongy). Asymmetric body Lack of body organizaiton. Structure.
Lack of body organizaiton
Spicules as structural component
Choanocyte for water flow and feeding
In Human Intestine
In Pig Muscle
nervous system consists of a brain connected to a ventral solid nerve cord, with a ganglion in each segment
It may be doubted whether there are many other creatures which have played so important a part in the history of the world
Charles Darwin, 1881
because of the size and importance of this phylum, it is mainly divided into four further classes:
- crustacea: with very hard exoskeleton
- insecta : body with three parts and three pairs of legs
- arachnida: body divided into two parts with four pairs of legs
- myriapoda: with many segments and legs
Crustacea contains 30,000 mostly marine species. A few species live in freshwater. For example: lobsters, crabs, crayfish, shrimp, etc.
Marine Copepod (Crustacean), Actitius sp.
Insects are the largest group, with probably over one million identified and named species.
Insects live in almost all terrestrial and freshwater habitats, with a few species living in the oceans.
These contribute to insects that they are the most successful group of animal, and are the least likely to become extinct.
Fruit flyFruit Fly. The insect body is divided into head, thorax (with wings), and a segmented abdomen. The compound eye of insects is also quite prominent.
control of populations of harmful invertebrate species (including other insects)
Cockroach - can transmit dieseas
Bee - a born pollinator of flowers
Ant - sometimes bite the wooden furniture