NEET BIOLOGY

Detailed explanation-1: -Invertebrates (Sponges, Cnidarians, Flatworms, Roundworms, Mollusks, Arthropods, Annelids, and Echinoderms)

Detailed explanation-2: -The sponges and the cnidarians represent the simplest of animals. Sponges appear to represent an early stage of multicellularity in the animal clade. Although they have specialized cells for particular functions, they lack true tissues in which specialized cells are organized into functional groups.

Detailed explanation-3: -Sea sponges are one of the world’s simplest multi-cellular living organisms. Yes, sea sponges are considered animals not plants. But they grow, reproduce and survive much as plants do. They have no central nervous system, digestive system or circulatory system – and no organs!

Detailed explanation-4: -Answer and Explanation: Despite what appears to be similarities with plants, sponges are considered animals for several reasons. Some of these include the facts that their cells lack a cell wall, they are multicellular organisms, and they reproduce using sperm cells.

Detailed explanation-5: -An invertebrate is an animal without a backbone. In fact, invertebrates don’t have any any bones at all! Invertebrates that you may be familiar with include spiders, worms, snails, lobsters, crabs and insects like butterflies. However, humans and other animals with backbones are vertebrates.