Question

The outer covering of an adult sea squirt is called the .

mantle

exoskeleton

shell

tunic

Why are sponges considered metazoans and all other animals considered eumetazoans?

		Sponges are prokaryotes, whereas other animals are eukaryotes.
		Sponges lack true tissues, whereas other animals have true tissues.
		Sponges do not have heads like other animals.
		Sponges are colonial organisms, whereas other animals are multicellular organisms.

What do bivalves and tunicates have in common?

		They are both close relatives of vertebrates.
		They are both soft-bodied lophotrochozoans.
		They are both filter feeders.
		They both have larvae with notochords.

Answer 1

Question 1 answer- tunic

Explanation- Sea squirts belongs to class Ascidiacea. The Ascidiacea is a paraphyletic class in the subphylum Tunicata. Ascidians are characterized by a tough outer "tunic" made of the polysaccharide cellulose.

Question 2nd answer- Sponges lacks true tissues whereas other animals have true tissues.

Question third answer- Both of them are filter feeders.

Explanation- A bivalve takes in water that has plankton and other things floating in it. Anything that is small enough to fit inside the hole of its incurrent siphon enters the bivalve. When the floating material comes in, it gets stuck in slimy mucus that is on the surface of the bivalve's gills. The food is moved down to the mouth, which is on the other side of the siphon. Food is digested in the bivalve's stomach and intestine, and everything that is not digested goes out through the other siphon, with water.

Nearly all tunicates takes their food by filtering sea water through their bodies. Ascidians are typical in their digestive processes, but other tunicates have similar systems. Water is drawn into the body through the buccal siphon by the action of cilia lining the gill slits. To obtain enough food, an average ascidian needs to process one body-volume of water per second.