Introduction to Animals *Invertebrates*

Domain: Eukarya Kingdom: Animalia All animal cells are eukaryotic which means the all have a nucleus and membrane bound organelles Animals that cannot make their own food are known as heterotrophs All animals are made up of many cells or multicellular.

Domain: Eukarya Kingdom: Animalia Animals are classifies by the presence of a backbone, vertebrate, or lacking a backbone, invertebrate. All animals at some point in their life do move and are called motile. Some animals that do not move during a stage in their life are called sessile.

Breaking up an Animal… Dorsal Anterior Posterior Ventral

Posterior Dorsal Ventral Anterior

Symmetry Animals can be described by their arrangement of body parts, or symmetry. Asymmetrical - Having parts that fail to correspond to one another in shape, size, or arrangement; lacking symmetry. Radial - Symmetry around a central axis Bilateral – Able to be divided into symmetrical halves on either side of a unique plane.

Animals are described according to their arrangement of body parts or symmetry.

Phylum: Porifera These are the sponges. They are known mostly for being filter feeders. No distinct tissues or organs No Gut No distinct symmetry No circulatory system No nervous system The “simplest” of animals.

Phylum Cnidaria These are hydras, jellyfish and anemones. Two tissue layers Radial symmetry Blind Gut No circulatory system Nervous system: network of nerve cells

Phylum Cnidaria Each organism contains tentacles that contain stinging cells known as nematocysts.

Hydra

Man-o-War

Coral

Phylum Platyhelminthes These are the flatworms Three tissue layers Bilateral symmetry Blind gut No circulatory system Nervous system: small bundles of nerves (ganglia), two ventral nerve cords

Phylum Platyhelminthes Tapeworms are the most well known flatworms. Each section of the tapeworm is called a proglottid. It contains both male and female reproduction structures.

Phylum Platyhelminthes You can get a tape worm by eating undercooked meat.

Flukes

Planaria

Phylum Nematoda These are the roundworms. Three tissue layers Bilateral symmetry Complete gut Contains pseudocoel Circulatory system: present Nervous system: small bundles of nerves (ganglia), two nerve cords

Wuchereria Bancrofti worm that can cause elephantiasis.

Hookworm

Heartworms

Phylum Rotifera These are the wheeled animals. Complete digestive tract with mouth and anus Nervous System: small brain from which a number of nerves extend throughout the body with a simple layout. Rotifers typically possess one or two pairs of short antennae and up to five eyes. Microscopic Live in fresh water

Rotifers

Phylum Mollusca Molluscs are soft bodied. Some examples are octopus, bivalves, squid, snails, and slugs. All mollusks except the bivalves have a radula used for tearing their food Three tissue layers Bilateral symmetry Complete gut with anus Circulatory system: Usually open to large coelomic cavity; Nervous system: brain, with nerve cords and bundles (ganglia), brain very well developed in squids and relatives

Cuttlefish Octopus

Snails

Slugs Clams

Phylum Annelida These are the segmented worms. The 2 big groups are the earthworms and leeches. Three tissue layers Bilateral symmetry Complete gut with anus Closed circulatory system Nervous System: brain, with nerve cords and bundles (ganglia)

Earthworm Leeches

Phylum Arthropoda This means jointed foot. These all have segmented bodies and paired appendages. This phylum is HUGE!!! Three tissue layers Bilateral symmetry Complete gut with anus Segmented Open circulatory system Nervous System: brain, with nerve cords and bundles (ganglia), Has compound eyes

Arachnids

Crustaceans

Centipedes Millipedes

Insects

Horseshoe Crabs

Phylum Echinodermata This means spiny skin. They move with tube feet. Three tissue layers Radial symmetry, sometimes even bilateral symmetry Blind sac like gut with reduced anus Circulatory system open Nervous system: major nerves extending from nerve ring, no brain

Starfish

Brittle Stars Sand Dollars

Sea Urchins

Useful Vocab Coelom – body cavity, where many organs are housed Pseudocoelom – “false” body cavity; contains no mesodermal cells; organs have no “lining” of these cells. Deuterostomes -in deuterostomes, the first opening (the blastopore) becomes the anus, while in protostomes it becomes the mouth. Notochord – supporting rod running the length of the body in chordates (becomes the vertebral column in vertebrates