Question

Questions 1-4 concern general information about each of the invertebrate phyla we discussed this semester. If none of the choices are appropriate, type ‘not applicable’.

1. Phylum Porifera (6)

Highest level of organization (cellular, tissue, organ)

Type of symmetry (asymmetry, radial symmetry, pentamerous radial symmetry, bilateral

symmetry)

Number of germ layers (diploblastic, triploblastic)

Type of body cavity (acoelomate, pseudocoelomate, coelomate)

Development pattern (protostome, deuterostome)

Feeding method (filter feeder, suspension feeder, deposit feeder, predator, herbivore)

2. Phylum Cnidaria (6)

Highest level of organization (cellular, tissue, organ)

Type of symmetry (asymmetry, radial symmetry, pentamerous radial symmetry, bilateral

symmetry)

Number of germ layers (diploblastic, triploblastic)

Type of body cavity (acoelomate, pseudocoelomate, coelomate)

Development pattern (protostome, deuterostome)

Feeding method (filter feeder, suspension feeder, deposit feeder, predator, herbivore)

3. Phylum Ctenophora (6)

Highest level of organization (cellular, tissue, organ)

Type of symmetry (asymmetry, radial symmetry, pentamerous radial symmetry, bilateral

symmetry)

Number of germ layers (diploblastic, triploblastic)

Type of body cavity (acoelomate, pseudocoelomate, coelomate)

Development pattern (protostome, deuterostome)

Feeding method (filter feeder, suspension feeder, deposit feeder, predator, herbivore)

4. Phylum Platyhelminthes (5)

Highest level of organization (cellular, tissue, organ)

Type of symmetry (asymmetry, radial symmetry, pentamerous radial symmetry, bilateral

symmetry)

Number of germ layers (diploblastic, triploblastic)

Type of body cavity (acoelomate, pseudocoelomate, coelomate)

Development pattern (protostome, deuterostome)

Answer 1

1. Phylum Porifera:

Highest level of organization- Cellular- here each cell performs a unique specialised function of digestion or respiration, etc.

Type of symmetry- Asymmetry- the division of body that doesn't result in two equal halves.

Number of germ layers- Diploblastic- they have on the two germ layers: ectoderm and endoderm except the mesoderm.

Type of cody cavity- Acoelomate- they do not have a body cavity.

Development pattern- Not applicable.

Feeding method- Filter feeder- they have structures like filters that filter the suspended particles present in water and then consuming all the edible matter or food substances.

2. Phylum Cnidaria:

Highest level of organization- Tissue- group of specific cells combine together to form a tissue that performs a specialized function.

Type of symmetry- Radial- this symmetry is where the body is divided into symmetric halves from planes apart from the principal axis as in sunrays.

Number of germ layers- Diploblastic- they have on the two germ layers: ectoderm and endoderm except the mesoderm.

Type of body cavity- Acoelomate- they do not have a body cavity.

Development pattern- Not applicable

Feeding method- Filter feeder- they have structures like filters that filter the suspended particles present in water and then consuming all the edible matter or food substances.

3. Phylum Ctenophora:

Highest level of organization- Tissue- a group of specific cells combine together to form a tissue that performs a specialized function.

Type of symmetry- Radial or Biradial Symmetry- Radial+ Bilateral= Biradial symmetry. Here two planes divide the organism into symmetrical halves. Two planes pass through the principal axis; both left and right along with top and bottom.

Number of germ layers- Diploblastic- they have on the two germ layers: ectoderm and endoderm except the mesoderm.

Type of body cavity- Acoelomate- they do not have a body cavity.

Development pattern- Not applicable

Feeding method- Deposit feeder -They feed on tiny organisms or anything they come across like plankton. But since they swim towards food they are deposit feeders.

4. Phylum Platyhelminthes:

Highest level of organization- Organ- here the specific tissues combine together to form a organ that performs specific functions. Here it has digestive and reproductive system.

Type of symmetry- Bilateral- they can be divided into two equal or symmetric halves that are mirror images.

Number of germ layers- Triploblastic- since they have all three germ layers: endoderm, mesoderm and ectoderm.

Type of body cavity- Acoelomates- they do not have a body cavity.

Development pattern- Protostomes- since their blastophore gets developed into a mouth instead of an an-al opening, they are called protostomes.

Feeding method- Suspension feeder- they feed on plankton, phytoplankton, detritus or dead materials that are suspended in the water.