rigure 28.8n, oross tionas woult appear under the microscope Comparison of Earth
ID: 133724 • Letter: R
Question
rigure 28.8n, oross tionas woult appear under the microscope Comparison of Earthworm and Clam State three distinct differences between earthworm anatomy and clam anatomy 3. Annelid Diversity Examine various types of annelids that your instructor may have on display. Note that the polychaetes' many setac differ from other annelids by having a well-differentiated anterior region with specialized sense organs and paired appendages, called parapodia, on most segments. Some annelids are active predators and others are tubeworms that capture food by means of cilia. The leeches, having an anterior and posterior sucker, are sometimes bloodsuckers, for which they are well known. Annelids have many of the features listed as most advanced in table 27.1. Justify this statement by answering the fol lowing questions. Why tube-within-a-tube with specialization of parts? Why bilateral (with cephalization in some)? Why true coelom? Why segmented? 28Explanation / Answer
Comparison
1. Clams possess a muscular foot as locomotory organ and mantle as external covering and radula as feeding organ to survive in the mud whereas the earthworm do not possess these, it is soft bodied.
The body is segmented into 100-150 segments and segmentation helps in locomotion and providing flexibility.
2. Clams possess siphons for respiration(excurrent and incurrent).while earthwor respires through its skin.
3. Clams have open circulatory system whle earthworm has closed circulatory system.
Discussion
Tube within tube specialisation in annelids - It is known as tube within tube because of the presence of fluid filled cavity between digestive tube and body wall.
Bilateral symmetry
The body segments are morror images along the saggital plane. It provides the streamlined body shape that would be advantageous for survival in deep oceans, lakes, water filled habitat.
Cephallisation occurs to place all the sensory organs at the anterior end while at the posterior end the tail is present. The placement of sensory organs are placed in the anterior end to facilitate better perception.
True coelom-
Secondary body cavity which arises from mesodermal splitting. It surrounds internal organs and functions as hydrostatic skeleton which aids in locomotion.
Segmented
facilitates movement by rhythmic contaction and expansion of the segments. Different segments houses the organs.
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