Question

Jimmy looked at his pond water and saw these little creatures moving. They are not worm-like, but he heard that they are pseudocoelomates. What are there characteristics?

Answer 1

In the pseudocoelomates (pseudo- false, coelom-body cavity) , the body cavity is not lined by the mesoderm (a germinal layer) and is a remnant of primary body cavity called blastocoel . The mesoderm is instead scattered as pouches in between the other two germinal layers i.e., ectoderm and endoderm.

The charecteristics of pseudocolemates that Jimmy had observed:

• they are triploblastic (posses three germinal layers - ectoderm, mesoderm, endoderm)
• they are bilaterally symmetrical (the body is divided into identical left and right halves in only one plane)
• unsegmented
• the body is covered by a transparent, tough and protective collagenous cuticle (exoskeleton)
• their uppermost layer i.e epidermis is syncytial (multinuclear)
• they possess a complete alimentary canal or digestive system consisting of a muscular pharynx that helps in grinding the food.
• the nervous system consists of a prominent ganglia and nerves
• tge sense orgns are cuticular depressions near the head region
• sexes are seperate (males and females are distinct)
• very often, the females are longer than the males(sexual dimorphism)
• either oviparous or viviparous
• the development is mostly direct i.e without any larval stage.