Identify the distinguishing characteristics of member of Phylum Cnidaria, including symmetry, number of embryonic tissue layers, unique structures, skeleton and polymorphism (polyp and medusa), place Cnidaria on a cladogram Compare and contrast how a general polyp and a medusa feed Describe why a nerve net was such a major evolutionary adaptation Describe the characteristics of the four classes of Cnidarians Label the following on a drawing: tentacles, mouth, anus, gastrovascular cavity, cnidocytes, nerve net Solution Answer1) Symmetry- Radially symmetrical body Number of embryonic tissue layers- two (endoderm and ectoderm) Unique structures- Stinging cells (Cnidocytes) Skeleton- Hydrostatic skeleton Polymorphism (polyp and medusa)- polyp is a flower like solitary form and medusa is a free- floating miniature of cnidarians. Answer 2) a tubular shaped body form is called as polyp. They are sessile and are found as attached bottom (basal plate) to a solid surface with the opened mouth at the top. while medusa is an umbrella or bell shape form, having their mouth facing downwards. And they are free floating. Being a sessile, polyp filter their food from the water by their tiny-beating cilia. While medusas are free floating and motile so they can trap their feedings, and need not to filter the water all the time though these structures were more related to the sexual reproduction. Answer 3) Nerve net is a diffused framework of neurons in the body which can transmit signals/impulse in different directions from a single point of stimulus. This became a major evolutionary adaptation because it allowed the organism to sense the environmental stimulus from any region of its body and respond accordingly. This allowed the readily development and motion of different body parts such as limb like structures. Answer 4) These are the four classes of cnidarians. Hydrozoa are diploblastic and multicellular animals. Which has only mouth opening. They have a fixed polyp stage and the reproductive medusa stage. They have the gonads as well. Scyphozoan are present in medusoid forms. They have tentaculocysts as Sense organs. They have Velarium in endodermal canal (Acraspedote). They endodermal gonads. Anthozoan are present only in polyp forms. Their medusa stage is absent. They have Mesenteries which bear nematocyst. They also possess endodermal Gonads. Cubozoan looks like the jelly fish and called as jelly boxes. They possess box shaped medusa and they share typical characteristics of scyphozoans..

1. Identify the distinguishing characteristics of member of Phylum Cnidaria, including symmetry,
number of embryonic tissue layers, unique structures, skeleton and polymorphism (polyp and
medusa), place Cnidaria on a cladogram
Compare and contrast how a general polyp and a medusa feed
Describe why a nerve net was such a major evolutionary adaptation
Describe the characteristics of the four classes of Cnidarians
Label the following on a drawing: tentacles, mouth, anus, gastrovascular cavity, cnidocytes,
nerve net
Solution
Answer1) Symmetry- Radially symmetrical body
Number of embryonic tissue layers- two (endoderm and ectoderm)
Unique structures- Stinging cells (Cnidocytes)
Skeleton- Hydrostatic skeleton
Polymorphism (polyp and medusa)- polyp is a flower like solitary form and medusa is a free-
floating miniature of cnidarians.
Answer 2) a tubular shaped body form is called as polyp. They are sessile and are found as
attached bottom (basal plate) to a solid surface with the opened mouth at the top. while medusa is
an umbrella or bell shape form, having their mouth facing downwards. And they are free
floating. Being a sessile, polyp filter their food from the water by their tiny-beating cilia. While
medusas are free floating and motile so they can trap their feedings, and need not to filter the
water all the time though these structures were more related to the sexual reproduction.
Answer 3) Nerve net is a diffused framework of neurons in the body which can transmit
signals/impulse in different directions from a single point of stimulus.
This became a major evolutionary adaptation because it allowed the organism to sense the
environmental stimulus from any region of its body and respond accordingly. This allowed the
readily development and motion of different body parts such as limb like structures.
Answer 4) These are the four classes of cnidarians.
Hydrozoa are diploblastic and multicellular animals. Which has only mouth opening. They have
a fixed polyp stage and the reproductive medusa stage. They have the gonads as well.
Scyphozoan are present in medusoid forms. They have tentaculocysts as Sense organs. They
have Velarium in endodermal canal (Acraspedote). They endodermal gonads.
Anthozoan are present only in polyp forms. Their medusa stage is absent. They have Mesenteries
which bear nematocyst. They also possess endodermal Gonads.

2. Cubozoan looks like the jelly fish and called as jelly boxes. They possess box shaped medusa
and they share typical characteristics of scyphozoans.