HORTICULTURE

Detailed explanation-1: -Animals can be classified into 2 main groups: vertebrates and invertebrates. Invertebrates are animals without a backbone. Vertebrates have an internal skeleton (endoskeleton) made of bones. Most but not all invertebrates have a hard outer casing called an exoskeleton.

Detailed explanation-2: -Worldwide in distribution, they include animals as diverse as sea stars, sea urchins, earthworms, sponges, jellyfish, lobsters, crabs, insects, spiders, snails, clams, and squid.

Detailed explanation-3: -A nerve cord is enclosed by vertebrae-individual bones that make up a vertebrate’s spine. Vertebrates have well-developed sensory organs, a respiratory system with either gills or lungs, and a bilateral symmetry with an advanced nervous system that further distinguishes them from invertebrates.