1. Complex Worms
2. Horseshoe Crown Bearing Animals
3. Soft Bodied Animals
4. Jointed Legged Animals
5. Spiny Skinned Animals
6. Notochord Animals

Phylum Annelida

1. Elongate body divided into segments
2. Internal structures repeated
3. Grow by adding new segments at rear
4. No hard skeleton
5. Move by waves of muscle contraction along body wall

Bristle Worms

1. Class Polycheata
2. Clumps of bristles on sides of each segment
3. Paired paddle-shaped appendages
4. Many with gills
5. Head often well developed
6. Often have feeding appendages associated with head

Phylum Bryozoa

1. Individuals of sessile colony in shelly, box-shaped compartments
2. Erect, branching or encrusting forms
3. U-shaped tentacular crown (Lophopore) used in feeding

Phylum Mollusca

1. Soft visceral mass
2. Mantle covers the body
3. Mantle cavity contains gills
4. Outer, calcareous shell (exoskeleton) produced by mantle
5. Muscular foot for locomotion

Chitons

1. Class Polyplacophora
2. Eight shelly plates
3. Creeping foot
4. Radula

Snails and Slugs

1. Class Gastropoda
2. One shell or shelless
3. Operculum to close shell opening
4. Creeping foot
5. Radula
6. Well developed head

Clams and Oysters

1. Class Pelecypoda or Bivalvia
2. Two shells hinged by ligament
3. Muscles hold shells together
4. Siphon tubes to direct water flow through shell
5. Hatchet-shaped foot for burrowing or reduced foot
6. No radula
7. No head

Nautili, Squid, and Octopi

1. Class Cephalopoda
2. Well developed head with large brain and advanced eyes
3. Shell large and external, reduced and internal, or absent
4. Tentacles with suction cups
5. Jet propulsion

Phylum Arthropoda

1. Soft joints between segments and parts of legs
2. Stiff, segmented exoskeleton
3. Growth follows molting
4. Body divided into regions
5. Well developed head
6. Many have compound eyes

Hard-Shelled Arthropods

1. Class Crustacea
2. Calcareous exoskeleton
3. Gills associated with legs
4. Legs specialized for walking, grasping, and swimming

Phylum Echinodermata

1. Endoskeleton of calcareous plates
2. Spines or tubercles project from endoskeleton
3. Pentamerous, radial symmetry
4. Water vascular system, podia & gills

Sea Stars

1. Class Asteroidea
2. Star-shaped body with disc and arms
3. Arms grade into disc
4. Stiff skeleton
5. Oriented with oral side down
6. Rows of tube feet in grooves on underside of arms

Brittle Stars

1. Class Ophuroidea
2. Central disc with narrow, elongate arms
3. Flexible skeleton
4. Oriented with oral side down
5. No tube feet
6. Arms move in serpentine fashion

Feather Stars

1. Class Crinoidea
2. Small, stalk-like central body
3. Long, feathery arms
4. Oriented with oral side up

Urchins

1. Class Echinoidea
2. Hard, stiff skeleton called test
3. Globular to flattened, circular shape
4. Spines protrude from test
5. Oriented with oral side down
6. Tube feet arranged in rows

Sea Cucumbers

1. Class Holothuroidea
2. Soft, fleshy body with highly reduced skeletal elements
3. Tube feet arranged in rows
4. Ring of tentacles around mouth
5. Bilateral symmetry
6. Oriented on side with anterior mouth
7. Respiratory trees and cloaca

Phylum Chordata

1. Have the following 5 characteristics during some part of life.

   A. Notochord (stiff dorsal rod)

   B. Dorsal, hollow nerve cord

   C. Pharyngeal gill slits

   D. Segmented muscles

   E. Post anal tail

Tunicates or Sea Squirts

1. Subphylum Urochordata
2. Body with sac-like covering called tunic
3. Large, internal basket
4. Incurrent and excurrent siphons
5. Tadpole larvae has all chordate characteristics
6. Dramatic metamorphosis

Sea Lancelets

1. Subphylum Cephalochordata
2. Fish-like body
3. Adult has all chordate characteristics
4. No vertebral column