At 5pm, we had TAXONOMY. It was quite an interesting class with no test. Lol..... . Today we discussed PHYLUM ANNELIDA. here are some of its features :
They are large and spacious, segmented metamerically, they have nephridria, they can be with or without chaetae (legs), they have well developed nervous and circulatory system, some are parasitic in nature.
They are the first set of Coelomate animals, they are called Eucoelomates.
The classes are:
1. Arthiannelida: Fresh water annelids with fairly segmented bodies. Eg. Polygordrin sp
2. Oligarchaetae: Both terrestrial and fresh water annelids, they have both sexes and have 4 pairs of chaetae (legs) on each segment of their bodies. Eg Lumbricus terrestrial (earthworm).
3. Polychaetae: More segmented morphologically, they exhibit cephalization(distinct head segment), they have 2 pairs of legs at each segment. They live in Seattle water only. Eg. Neries diversicolor.
4. Hirudineae: No definite body segmentation, they have annuli (false segment), they are parasitic, contains 2 sucker at their head and tail, no chaetae present as they move by muscular contraction and elongation, they also possess anticoagulant in their saliva called thirudin which enables them to suck blood easily. Eg. Hirudo medinesis (leech).
Morpholical features of Earthworm.
* They are cylindrical in shape, well segmented but not fully.
* At max length, they are one foot long, they have two parts (ventral - dark in color and dorsal - light in color).
* All parts of the body are segmented except the mouth and tail, the first and last segments lack Chaetae.
* On the body of the earthworm, (except 1,2,3 and last), there is nephridrio pore aperture used for my excretion..
* Oviduct and spermateca and in a confined segment of the body.
The lecture had to leave earlier due to the news of the death of an ND 3 student(his project student). MAY HER SOUL REST IN PEACE. AMEN.
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