InvertebratesKingdom Animalia

Kingdom Animalia• 97% Invertebrates (lack a backbone)• ExamplesExamples - worm, jellyfish, lobster, spiders, etc.

Patterns of Symmetry• SymmetrySymmetry - Arrangement of body parts around a point or

central axis.Four typesFour types:• AsymmetricalAsymmetrical - no definite symmetry• SphericalSpherical - shaped like globes• BilateralBilateral• RadialRadial

Radial Symmetry

• Divided into halves by anyany plane that passes through its longitudinal axis.• Example - hydra,

starfish

Bilateral Symmetry• Divided into halves by

placing oneone specific plane through the longitudinal axis of an organism.• Example - butterfly

Terminology

• Cephalization - An adaptation that allows organisms’ sensory organs to enter an environment first.• Specialization - An adaptation of a cell for a

particular function.• Anterior - front end• Posterior - hind end• Dorsal - top• Ventral - bottom

Patterns of Development

• Zygote - Embryo - Blastula - Gastrula• Blastopore, or

depression, is produced in the blastula stage.• Gastrula stage -

Formation of ectoderm, endoderm, & mesoderm

Invertebrate Phyla - Phylum Porifera

• Filter feeders• Non-motile(sessile)• Asexual/sexual

reproduction• Example - Sponges

Phylum Cnidaria• Shapes - polyp,

medusa, mixed colonies.• Body parts - tentacles,

nematocysts (stingers), gastrovascular cavity• Asexual/sexual

reproduction; hermaphroditic• Example - Jellyfish

More phyla...• Phylum PlatyhelminthesPhylum Platyhelminthes - free-living & parasitic, marine,

asexual/sexual reproduction - Examples-flatworms (flukes, planaria, tapeworms)• Phylum NematodaPhylum Nematoda - free-living & parasitic; roundworms -

Example-Ascaris, trichinella• Phylum RotiferaPhylum Rotifera - free-swimming; feed on algae, bacteria,

& protozoa - Example-Rotifers

Phylum Annelida

• True body cavity, or coelemcoelem.• Body is segmented.• Well-developed organ

systems• Most annelids have

external bristles called setaesetae.

Earthworm Dissection