Question

1. List characteristics of ALL animals: 2. The basal animal that is NOW considered to be the ancestor of ALL animals (based on molecular evidence) belongs to the phylum 3. The clade RADIATA includes: 4. The clade BILATERIA is divided into two groups based on embryology. Most animals belong to the clade. The clade known as Deuterostomes includes only these groups: 5. Humans belong to which phylum? 6. Which PHYLUM that we have discussed in class is most closely related to humans? 7. List the three coelom types and examples of each. 8. What is cephalization? Why is it important? When did it arise? 9. What is segmentation? Why important? Which groups of animals have segmentation?

Answer 1

Q1; All animals are multicellular eukaryotes.

All animal cells lack cell wall.

All animals are heterotrophs.

All animals have sensory organs in them.

All animals have the ability to move.

All animals have sexual reproduction.

Q2; Recently it has been found out to be comb jelly and not sponges as was thought earlier. comb jelly belongs to phylum Ctenophora.

Q3; The clade radiata includes the eumetazoan animals with radial symmetry, although it is not used by all biologists.

It includes; cnidarians and ctenophores

Q4;Most animals belong to the clade Protostome, which includes those animals in which the first opening in the embryo development becomes the Mouth.

Deuterostomes are those animals in which, during the embryonic development the first opening(the blastopore) becomesthe anus.

There are three main clades in deuterostomes :

1. chordata 2. echinodermata 3. hemichordata

Q5; Humans belong to the phylum Chordata.

Meaning that humans have a backbone and a spinal cord(characterstic of the chordates).

Q6; Echinoderms are the phylum most closely related to humans. here are some reasons for the same;

like humans, echinoderms also have a notochord at larval stages which eventually disappears as they mature.

they posses pharyngeal gill slits like humans, the nerve cells and a muscular tail extending past the anus.

Q7; Coelom is the fluid filled body cavity present between alimentary canal and the body wall.

There are three types of coelom;

1. acoelom (coelom is absent, at its place a spongocoel is found) eg; porifera, coelenterata, ctenophora, platyhelminthes

2. pseudocoelom (true coelom is not present, blastocoel is only partly filled with mesodermal cells and the mesoderm lines only the body wall and not the gut). eg; aschelminthes

3. eucoelom (true coelom lined on both sides by the mesodermal cells, is found). eg; annelida, arthropoda, mollusca, echinodermata, hemichordata, chordata`

Q8;

Q9;