C 4. Write the general characteristics of phylum platyhelminthes.

1.	C 4. Write the general characteristics of phylum platyhelminthes.
Answer» General characteristics of phylum Platyhelminthes (Platys: flat; helminthes: worms) Kingdom: Animalia Habitat: mostly parasitic, few are free living in sea water or fresh water Grade of organization: Organ- system grade of organization Symmetry: Bilateral symmetry and Body is dorso-ventrally flattened Germ layer: Triploblastic. Ectoderm is very specialized with distinct epidermis Coelom: Absent (acoelomate). Digestive system: incomplete or absent No mouth (oral opening directly into pharynx). No true stomach structure (pharynx opens into a complex “intestinal” structure). In tapeworms, Direct absorption of soluble nutrients by cells and tissues. Excretory system: Protonephridia with Flame cell Respiration: by simple diffusion of gases through body surface Circulatory system: Absent Reproduction Sexual: by gamatic fusion in hermaphrodite species Asexual : by regeneration and fission Fertilization: internal. Life cycle is complex involving one or more hosts.

Answer»

General characteristics of phylum Platyhelminthes

(Platys: flat; helminthes: worms)

Kingdom: Animalia

Habitat: mostly parasitic, few are free living in sea water or fresh water

Grade of organization: Organ- system grade of organization

Symmetry: Bilateral symmetry and Body is dorso-ventrally flattened

Germ layer: Triploblastic. Ectoderm is very specialized with distinct epidermis

Coelom: Absent (acoelomate).

Digestive system: incomplete or absent

No mouth (oral opening directly into pharynx).

No true stomach structure (pharynx opens into a complex “intestinal” structure).

In tapeworms, Direct absorption of soluble nutrients by cells and tissues.

Excretory system: Protonephridia with Flame cell

Respiration: by simple diffusion of gases through body surface

Circulatory system: Absent

Reproduction

Sexual: by gamatic fusion in hermaphrodite species

Asexual : by regeneration and fission

Fertilization: internal.

Life cycle is complex involving one or more hosts.

Discussion