Diversity in Living Organisms

Nerve net found in many cnidarians is a part of more advanced nervous systems. Cytoplasmic processes join the nerve cells (neurons) of nerve nets. In cnidarians, the neurons are joined to epithelial receptors and to contractile cells. In vertebrates, nerve nets may be found around blood vessels and the alimentary tract. The nerve net is the simplest form of a nervous system found in multicellular organisms. Unlike, central nervous systems where neurons are typically grouped together, neurons found in nerve nets are found spread apart. This nervous system allows cnidarians to respond to physical contact. They can detect food and other chemicals in a rudimentary way. While the nerve net allows the organism to respond to its environment, it does not serve as a means by which the organism can detect the source of the stimulus. For this reason, simple animals with nerve nets, such as Hydra, will typically produce the same motor output in response to contact with a stimulus regardless of the point of contact. 

Unicellular organisms also require transporting mechanism in order to transport nutrients, enzymes, waste products etc. The transport mechanism in unicellular organisms is simpler than multicellular organisms. Unicellular organisms can transport substances in and out of the body by diffusion and osmosis.

Anapsida has a solid roof due to the absence of any temporal vacuities on skull.

• The anterior middle portion of vertebrae is known as centrum and a posterior vertebral arch known as the neural arch. 
• The procoelous vertebra is convex at the anterior side while convex at the posterior side. 
• Ophidia is a suborder that includes snakes and reptiles and has procoelous vertebrae.
• So option A is the correct answer

The living amphibians are divided into three subclasses:

The order Anura includes the amphibians like the frogs and toad. The basic characteristics of Anura species are 

Salientia is a Latin word which means 'to jump'. So, it is justified calling Anura as Salientia as frogs and toads have larger hindlimbs and forelimbs which helps them to leap. So, the correct answer is 'Anura'.

The characteristics of salamanders are as followed:

Chameleons are squamate reptiles belonging to the family Chamaeleonidae. They are cold-blooded vertebrates covered in scales, which places them firmly in the class Reptilia.

Bats are mammals, and a defining characteristic of mammals is the presence of hair or fur on their skin. Birds, in contrast, possess feathers.

Anapsid is a subclass of reptiles. An anapsid is an amniote whose skull does not have openings near the temples. The skull of anapsid are made by solid roof. It includes turtles and extinct Permian forms. 

Endemic means a species which is native to a place and is not found anywhere else in the world. Endemic basically means indigenous. The more endemic species at a place more is the biodiversity of that place. Another example includes the Nilgiri tahr, also known as Nilgiri Ibex is endemic to the Nilgiri Hills and some part of Western Ghats of Kerala.

Mollusc constitutes the second largest phylum in the animal kingdom which includes a group of animals living on land, in marine water, and in fresh water. Mollusks include both herbivores and carnivores animal. They eat both plants and small animals. In an aquatic ecosystem, a mollusk acts as primary consumers, so it belongs to second trophic level (T2).

Polar Adaptations refers to the unique adaptations that polar organisms have developed to survive in extreme cold and harsh conditions, such as thick fur, blubber layers, and specialized metabolic processes.