4.3 The Bilateral Worms

Match the following types of symbiosis to their descriptions

• the relationship is mutually beneficial.

• Mutualism:

  a relationship between two or more organisms where...

• one benefits and the other is harmed.

• Commensalism:

  a relationship between two or more organisms where...

• one benefits and the other is neither harmed nor benefited.

• Parasitism:

  a relationship between two or more organisms where

Identify the organism(s) that are bilaterally symetric.

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Which answer choice describes animals that have bilateral symmetry?

• Animals have that have a body that is shaped like a short or long cylinder or bowl and has symmetry around a central axis from which the body parts radiate. They have a posterior and anterior end.

• Animals that have a defined head end and rear end , a right and left side, and a top and bottom surface. Only one plane of symmetry will divide the animal into equivalent halves.

• Animals that have a spherical body shape with body parts arranged around the center. There is no posterior or anterior and any plane passing through the center will divide the animal in equivalent halves.

Match the following

• top

• posterior

• bottom

• ventral

• rear end

• anterior

• head end

• dorsal

Match the bilateral worms' phyla and their common names.

• ribbon worms

• Nematoda

• segmented worms

• Annelida

• roundworms

• Platyhelminthes

• flatworms

• Nemertea

Which bilateral worm phylum has the simplest organization of organs and organ systems?

• Platyhelmenthes

• Nematoda

• Nemertea

• Annelida

Which phylum of bilateral worms has a proboscis?

• Platyhelmenthes

• Nematoda

• Nemertea

• Annelida

Which phylum of bilateral worms has many species that are parasitic?

• Platyhelmenthes

• Nematoda

• Nemertea

• Annelida

Which phylum of bilateral worms has a segmented body, a gut that travels the length of its body, and a distinct circulatory system?

• Platyhelmenthes

• Nematoda

• Nemertea

• Annelida

Match the following words to their definitions

• a pair of small, flattened extensions that extend from each body segment

• parapodia

• fluid-filled body cavity that contains specialized tissues

• Trochophore

• the free swimming, ciliated, planktonic larvae of certain invertebrates

• proboscis

• extensions of the body containing thin-walled blood vessels that allow for easy absorption of oxygen

• gills

• a venomous, spaghetti like appendage used for defense and to capture prey

• coelom