Long Answer Questions:
1. Although group platyhelminthes, nematoda and annelida consists of worms still they are different
from each other. Explain.
Answers
Answer:
platyhelminthes consists of flat worms.they are dorsoventrally flattened and they have a gastrovascular cavity or no digestive system. and they have no segment. example, planaria.
nematode is a unsegmented pseudocoelamate. ther is no circulatory system is present. and consists of round worms
annelida consists of segmented worms .they have a closed circulatory system and are coelamate. consists of earthworm and leeches.
Answer:
Platyhelminthes
. Body is flat, thin, soft and leaf like or ribbon like.
They have only one opening for intake of food and throwing out waste. Alimentary canal is absent. Body is bilaterally symmetrical, i.e., it can be divided into two identical halves only through a single plane.
• They mostly live as parasites on the body of other animals (hosts). Examples are tapeworm and liver fluke.
• Parasitic flatworms have hooks and suckers on their head. They help them attach to the host body.
Examples are liver fluke, tapeworm and Planaria
Nematoda
. Body is elongated, cylindrical, unsegment ed and bilaterally symmetrical.
→ Most of them live as parasites inside the body of other animals including humans. Some live in soil or water.
.They have a digestive system with two openings, the mouth and the anus.
Examples are filarial worm, Ascaris (round worm) and hookworm .
Annelida
. Mostly aquatic, some live in the moist soil. Some are parasitic like leeches.
. Body is elongated, soft and divided into ring-like segments.
. Digestive system is complete and exten straight from the mouth to the anus. They breathe through the moist body wa
. Body cavity is present.
. They have special organs for excretion called nephridia.
Examples are earthworm and leech .