Volvox

CLASSIFICATION OF VOLVOX​

Sub-division :- Algae

Class :- Chlorophyceae

Order :-  Volvocales

Family :- Volvocaceae

Genus :- Volvox

GENERAL CHARATERSTICS OF VOLVOX​ :-

• Thallus is multicellular, motile and a coenobial colony.
• Colonies are mostly spherical, rounded or oval in shape.
• It is hollow in the centre and cells are arranged in a single layer towards the periphery.
• Layer of cells is surrounded by a gelatinous mass which forms the outer and firm limiting layer.
• The number of cells in a colony varies from 500-6,500 according to the species.
• Each cell of the colony is connected with a few of the neighbouring cells by thin and delicate cytoplasmic strands.
• Each cell is enveloped by an individual gelatinous sheath.
• All the cells of a colony are typically chlamydomonad in shape, size and structure.
• Each vegetative cell is biflagellate, motile and ovoid. The two flagella are anteriorly inserted. A contractile vacuole is situated one each at the base of a flagellum.
• Cup-shaped chloroplast occupies much of the posterior part in which is situated a single pyrenoid. In the cavity formed by cup-shaped chloroplast lies a single nucleus, surrounded by cytoplasm.
• Cytoplasm is rich in volutin grains. Eyespot or stigma occupies anterio-Iateral position.

IDENTIFICATION

• Sub-division– Algae
  1. Presence of a simple thallus.
  2. Chlorophyll present
  3. Cell wall made of cellulose.
• Class– Chlorophyceae
  1. Presence of a definite nucleus
  2. Chloroplast present. grass green colour
  3. Presence of starch
  4. Reproductive structure motile and flagella equal in length.
• Order– Volvocales
  1. Vegetative cells flagellated
  2. Thallus motile.
• Family – Volvocaceae
  1. Thallus colonial
  2. Division of cells in longitudinal plane.
• Genus – Volvox
  1. Colony spherical or sub-spherical,
  2. Number of cells at least 500.