Question

please help me with this part of my lab reprot!! will rate and comment!!

Sketch a sea star showing external anatomy, a cross section of a sea star ray, and make a sketch showing internal anatomy, labeling the characteristics in bold where appropriate. Be sure to indicate the symmetry, type of digestive tract, and coelom in your sketch. Sketch and color-code the structures that derive from ectoderm-blue, from endoderm-yellow, and from mesoderm (if present)-red. Indicate the unique characteristics of the phylum in purple.

Answer 1

Starfish belongs to the phylum Echinodermata. The characteristic features of this phylum are as follows :

Characteristic Features of Phylum Echinodermata

• exclusively marine animals.
• The larval forms exhibit bilateral symmetry and adult forms have radial symmetry.
• triploblastic.
• organ system grade of organization.
• They have a true coelom.
• The body is uniquely shaped(star-like, elongated or spherical)
• The body is unsegmented without a head.
• The body surface is covered with calcareous spicules.
• Body cavity has a distinguishing water vascular system that serves as respiratory, circulatory, excretory as well as in locomotion.
• Tube feet help in locomotion.
• Nervous system - consists of a nerve ring and radial nerve cords. brain is absent
• Respiration occurs through tube feet and gills.
• Sexes are separate.
• external fertilization
• Regeneration

Ectoderm forms the exterior most layer. it forms the skin and the nervous system

Mesoderm will form the muscle and circulatory system

Endoderm will form the lining of gut and other internal organs

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