Question

Into which classes are platyhelminthes divided? How can these classes be described and what are some representative species in each of them?

Answer 1

These are (Platys: flat; helminths: worms) belongs to kingdom of Animalia and mostly parasitic, few are free-living in seawater or fresh water and do have organ system grade of organization and shows bilateral symmetry and body is flattened and they are in triploblastic in nature with coelom is absent (acoelomate) and the digestive system is incomplete or absent

Classification of Phylum Platyhelminthes

Based on body shape, mouth position and habitat the phylum of Platyhelminthes are divided into three classes

Class 1: Turbellaria

Class 2: Trematoda

Class 3: Cestoda

Class 1 Turbellaria

• Mostly Free-living freshwater organism
• The body has the dorsoventral with flat like structure
• Hooks and sucker are absent

Examples

Planaria, Bipalium, Otoplana, Notoplana

Class 2 Trematoda

• Most of them are parasitic in nature
• Body looks like in the form of dorsoventrally flattened leaf-like structure
• Hooks and sucker are present

Examples

Fasciola hepatica (Liverfluke), Diplozoon,

Class 3 Cestoda

• These are exclusively parasitic in nature
• Body divided into dorso-ventrally flattened tape-like structure
• Hooks and sucker are present
• Digestive system completely absent
• Excretion is performed with protonephridia with flame cells

Examples

Taenia spp ( tapeworm), Convoluta, Echinobothrium