Kingdom Animalia

Subdivisions Phylum Porifera (Sponges) Phylum Cnidaria (Jellyfish/Anemones) Phylum Platyhelminthes (Flatworms) Phylum Nematoda (Roundworms) Phylum Annelida (Segmented Worms) Phylum Mollusca (Mollusks) Phylum Arthropoda (Arthropods) Phylum Echinodermata (Starfish) Phylum Chordata (Vertebrates)

PLATYHELMINTHES: Flatworms Flatworms have no body cavity other than the gut. They even lack an anus; the same pharyngeal opening both takes in food and expels waste.

Marine flatworms Because of the lack of any other body cavity, in larger flatworms the gut is often very highly branched in order to transport food to all parts of the body.

Terrestrial flatworm about to attack an innocent earthworm The lack of a cavity also constrains flatworms to be flat; they must respire by diffusion, and no cell can be too far from the outside, making a flattened shape necessary.

Q & A: Why are flat worms flat?

The lack of a body cavity requires them to respire by diffusion. Answer: The lack of a body cavity requires them to respire by diffusion. No cell can be too far from the outside.

NEMATODA: Roundworms There are thousands of nematodes. Not only are there more than 15,000 known species of roundworms, they keep coming!

Roundworms cause many common diseases Some species of roundworm may contain more than 27 million eggs at one time and lay more than 200,000 of them in a single day.

Roundworms located in the eye

A roundworm being removed through the skin

Heartworms

ANNELIDA: Segmented Worms

Marine polychaetes “many bristles” There are about 9000 species of annelid known today including earthworms and leeches. “many bristles”

MOLLUSCA: There are over 50,000 known species of Mollusks, which makes them second only to the Arthropods in invertebrate phylum size.

a head, a visceral mass, and a "foot." Mollusks have 3 body regions: a head, a visceral mass, and a "foot." Mollusks have well developed body organs (nervous system, circulatory system, respiratory system, etc.) but lack body segmentation. Nudibranch

Blue-ringed octopus Caribbean octopus

Squid Among the Mollusks are some of the most well known of invertebrate sea creatures, like snails, clams, mussels, squid, and octopus.

Scallop

ECHINODERMATA: Starfish to Sea Cucumbers… Basket starfish Red Sea Urchin Common Characteristics: Endoskeleton,Water vascular system ("tube feet"), Gut complete, Decentralized nervous system, Marine.

Brittle Starfish

Sunstar Sea Cucumber Most starfish are predators, feeding on sessile or slow-moving prey such as mollusks and barnacles. Many, but not all, starfish are able to turn a portion of their stomachs out through the mouth, and thus digest food outside of the body.

Purple Sea Urchins

ARTHROPODA: Don’t let the Bedbugs bite! The largest phylum of creatures on Earth without a doubt is Arthropoda, both in terms of number of species and in total number of individuals. There are nearly 1 million species of Arthropods, with over 90% of them being insects.

House Fly

Termite Mounds The most obvious characteristic of arthropods is the external skeleton (technically, not really a shell). Not only does this exoskeleton protect the animal like a suit of armor, but it actually does serve as the animal's skeleton. The muscles of an Arthropod are connected to the inside of the exoskeleton.

What are some characteristics of Arthropods? Q & A: What are some characteristics of Arthropods?

Answer: Exoskeleton, Jointed legs, Segmented bodies.

CHORDATA: Chordates have their skeletons on the inside, a design that allows for growth without the need for molting. Of the approximately 50,000 living chordates, 97% are vertebrates.

Mature Sea Squirts Larva Sea Squirt Notochord Larva Sea Squirt A young tunicates, called a larva, resembles a tadpole and is able to swim freely by means of a tail. As it matures, the larva settles and metamorphoses losing its tail, its ability to move, and many of its chordate features. The nervous system disintegrates, and the adult form becomes essentially a sack with two siphons through which water enters and exits.

Whale Shark Characteristics of Chordates: A stiffening rod, called a notochord. Another chordate feature is a hollow nerve structure called a dorsal nerve cord. Structures called pharyngeal gill slits, or clefts.

Harbor Seal

Sea Lions

Loggerhead Sea turtle

Kookaburra

African Elephants

King Cobra

Why are sea squirts classified with the chordates? Q & A: Why are sea squirts classified with the chordates?

Answer: They develop a notochord during the larval stage and lose their chordate features only when maturing.

Body position and symmetry Some of the simplest animals have radial symmetry; the most complex have bilateral symmetry.

Bilateral symmetry Radial symmetry Radial Symmetry The body parts of a radially symmetrical animal are arranged around a central axis so that each part extends from the center. The animal can be cut along the axis in more than one plane to produce identical halves. Bilateral Symmetry Only one cut along the longitudinal axis will produce identical halves of a bilaterally symmetrical animal.

Anterior

Posterior

Dorsal

Ventral

Lateral