👉Phylum Ctenophora🦠🦠💨🐛🐛
👉Characters of Ctenophora👇👇👇👇
1. Eschboltz/Hatschek gave term Ctenophora.
2. They are free-swimming, marine, solitary, pelagic animals. No polymorphism and no attached stages were found.
3. The body is transparent, gelatinous, pear-shaped, cylindrical, or flat or ribbon-shaped.
4. They have a biradially symmetrical body along an oral-aboral axis.
5. They have an external surface with comb-like 8 ciliary plates for locomotion. Hence name as comb jellies.
6. They have a pair of long, solid, retractile tentacles.
7. Their body organization is cell- tissue grade.
8. Their body is acoelomate and triploblastic, with the outer epidermis, inner gastrodermis, middle jelly-like mesoglea with scattered cells, and muscle fibers.
9. Their digestive system contains the mouth, stomodaeum, complex gastrovascular canals, and 2 aboral anal pores.
10. They lack nematocysts.
11. They have special adhesive and sensory cell i.e. colloblasts or lasso cells present in tentacles which helps in food captures.
12. They lack skeletal, circulatory, respiratory, and excretory organs.
13. Their nervous system is diffused types and the aboral end bears a sensory organ, called statocyst.
14. They are monoecious (hermaphrodite); gonads are endodermal situated on walls of digestive canals.
15. Their development direct with characteristic cydippid larva.
16. They lack asexual reproduction and alternation of generation.
17. Regeneration and paedogenesis are common in them.
18. Phylum Ctenophora contains about 100 known species.
Examples-Mertensia , Pleurobrachia , HormiphoraMnemiopsis , BolinopsisCestum , Velamen
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