________________ are animals with backbones.
________________ are animals without backbones
________________is the balanced arrengement of body parts around a center point or along a center line.
________________ are simple invertebrates that have pores.
A ______________ is a small opening.
_______________________ are animals with stinging cells and hollow, saclike bodies that lack organs.
Many stinging-cell animals have armlike parts called _________________.
_________________ are the simplest worms.
A ________________ is a kind of flatworm that has a flattened, ribbonlike body divided into sections.
A ______________ is a young worm with a protective covering.
A ______________ is a common freshwater flatworm that is not a parasite.
_________________ are worms that have long bodies with pointed ends.
A ________________ is a roundworm that is a parasite of humans.
An _______________ is an opening through which undigested food leaves the body.
The __________________________ are worms with bodies divided into sections called segments.
______________________ are animals with a soft body that is usually protected by a hard shell.
The body is covered by a thin, fleshy tissue called a _______________.