Animals come in many shapes and sizes but they all have some things in common.

​Animals have all of these things in common.

​Even though animals come in MANY different shapes and sizes, live in many different habitats, and behave in countless different ways they all share these characteristics. Make sure you understand what each one means.

Animals Diversity

Animals are classified into at least 30 groups called "phyla". Nine of these phyla contain most of the animals that exist on Earth today.

Phylum Porifera

• The Sponges - the word porifera means "with PORES"

• simple body structure

• No nervous system or brain

• filter feeders

• free-living larval stage before becoming sessile adults (sessile means they stay in one place)

• all are aquatic

• most primitive animal

Phylum Cnidaria

• "cnidos" = "Stinging" cells on their tentacles

• Examples: sea anemone, corals, jellyfish, hydra

• soft bodies, no skeleton

• one opening for food to go in and waste to go out (gastric cavity)

• some are free-living, some are sessile as adults

• first animals to MOVE with muscles

• all are aquatic​

Phylum Platyhelminthes

• "Flatworms" (platy means "flat" + helminth means "worm"

• well developed muscular system

• brain and nervous system

• gastric cavity​

• no specialized circulatory, respiratory, or skeletal system.

• absorb oxygen and nutrients directly​

• many cause disease as parasites (parasites are organisms that live inside or on other organisms)

Phylum Nematoda

• "Roundworms"

• free-living in the environment or they can be parasitic

• live on land and in water

• absorb nutrients directly from the environment through their entire bodies

Phylum Mollusca

• Examples are snails, slugs, squids, octopuses, mollusks

• "soft body"

• many are fast movers; some by jet propulsion

• have organ systems​

• some have a shell

• a muscular "foot"

• some have very keen senses

Phylum Annelida

• "segmented worms"

• Examples are earthworms, leeches, tube worms,

• fluid-filled body

• move by hydrostatic pressure

• respire through their skin

• well-developed circulatory and digestive systems​

Phylum Arthropoda

• Examples are insects, spiders, scorpions, crabs

• Have an Exoskeleton (external skeleton)

• Paired, jointed appendages

• Many have appendages adapted for flight

• Live on land and in water

Phylum Echinodermata

• Echino = "spiny" + derm = "skin"

• sea urchins, sand dollars, sea cucumbers, sea stars

• All members live in the ocean

• Found in every depth of the ocean

• Can regenerate limbs, which allows them to reproduce on their own

Phylum Chordata

• animals with a spinal cord

• fish, amphibians, birds, reptiles, mammals

• bilateral symmetry; the right and left halves of the body mirror each other.

• well developed body systems

• adapted to many different environments