Question

Which of the following is not the correct match of animals and its habitats?
A) Hydra vulgaris - Seawater.
B) Hydra gangetic - Fresh water.
C) Obelia - Sea water.
D) Physalia - Sea water.

Answer 1

The dwelling place of an organism is called its Habitat.The above organisms are aquatic dwellers.They differ from each other based on the type of aquatic medium they live in.Most of the Hydra are almost freshwater dwelling, some live in ponds, lakes and so on.

Complete answer:
Hydras are mild sensitive to light, temperature and chemicals.They cannot bear extreme light and complete darkness, they prefer temperatures ranging between 20 to 25 degrees and cannot sustain adverse temperature, they are sensitive to food and consider inorganic and other harmful chemicals as toxins.

Obelia are the forms of hydrozoans which can be seen in both seawater and freshwater, usually found in the marine medium.They have two stages of life cycle such as polyp and medusa where medusa stage require marine condition and is found in the coastal region of sea, Physalia is also called as poetugese man of war due to their appearance, it is a colony which is found only in marine water, Pacific ocean, Indian ocean and Atlantic ocean are considered as its native region.As given in the hint most of the species of hydra are freshwater living, Hydra vulgaris dwell in freshwater not in sea water.

Hence option A is the correct answer.

Note: Hydra vulgaris belongs to class Hydrozoa and phylum Cnidaria, they are 10-30 mm in length and 1 mm in width.They are freshwater dwelling diffused in the temperate and tropical regions of the globe not found in marine conditions.