Question

In which animal there is no blood for the transport of nutrients?
A. Fish
B. Hydra
C. Sponges
D. Both B and C

Answer 1

Hint: Hydra and Sponges do not have a circulatory system. They are the simple unicellular organism.

Complete answer: Sponges are the simplest animals but they have a transport system.
1. Seawater is the medium of transport and is propelled in and out of the sponge by ciliary action.
2. Sponges do not have a nervous, digestive, or circulatory system. They rely on keeping up a constant water flow through their bodies to obtain food and oxygen and to remove wastes.
3. There is no heart, there are no veins or arteries, and sponges do not have blood.
4. Water is pulled into the sponge via internal choanocyte cells, which take in water through the sponge's outer pores.
5. Simple animals, such as the hydra lack specialized organs such as hearts and blood vessels, instead they use their skin as an exchange point for materials.
6. A hydra does not need an internal transport system. Its body wall which is only two cells thick encloses a central gastrovascular cavity that serves the digestion and distribution of substances throughout the body.
7. Hydra has a fluid-filled gastrovascular cavity where nutrients are absorbed. The hydra gets it oxygen from the water that entered the cavity and it gets rid of carbon dioxide through this cavity. The cells lining this cavity get nutrients for the body. This limits the size of an animal. To become larger, they need specialized organs and organ systems.

So, the answer is D. Both B and C

Note: The circulatory system consists of three independent systems that work together: the heart (cardiovascular), lungs (pulmonary), and arteries, veins, coronary and portal vessels (systemic).
The system is responsible for the flow of blood, nutrients, oxygen, and other gases, and as well as hormones to and from cells.
It is present in higher animals.