Invertebrate Animals

Before commencing to study from these notes, refer to Overview of Kingdom Animalia.


Phylum Porifera

  • Example: sponges
  • Invertebrate
  • Multicellular
  • Mostly marine, some freshwater
  • A sponge consists of an outer layer of covering cells, an inner layer of flagellated cells, and some cells in between. Water moves in through many small pores, and out through one large pore. Nutrients and oxygen are absorbed directly from the water into the cells.
  • No nervous, digestive, circulatory, respiratory, skeletal nor muscular systems
  • Reproduction - either asexual or sexual

Did You Know That...? If a sponge is cut into pieces, each small piece will regrow into a new individual organism. Also, since it has no nervous system, a sponge will feel no pain.


Phylum Cnidaria / Phylum Coelenterata


Phylum Platyhelminthes (Flatworms)


Phylum Nematoda (Roundworms)


Phylum Nemertea
(Ribbon Worms / Proboscis Worms)


Phylum Bryozoa (Moss Animals)

Did You Know That...? Madagascar is a conservation 'hot-spot' because of its abundant biodiversity.


Phylum Mollusca


Phylum Annelida ( Segmented Worms)


Phylum Arthropoda


CLASS CRUSTACEA


CLASS MYRIAPODA

Did You Know That...? Centipedes do not have 100 legs, nor do millipedes have 1000 legs. In fact, a centipede has 1 pair of legs per body segment, and a millipede has 2 pairs of legs per body segment. Another difference is that centipedes are carnivorous and can be poisonous, and millipedes are herbivorous.


CLASS ARACHNIDA / CLASS CHELICERATA

Did You Know That...? Spiders don't get caught in their own webs because they produce two types of web threads - non-sticky threads which provide structure for the web and on which the spider crawls, and sticky threads to catch the prey.


CLASS INSECTA

Did You Know That...? Only female mosquitoes suck blood. Male mosquitoes have a deeper hum than the shriller female hum. They make the humming sound by vibrating their wings.


Phylum Echinodermata