Is a lobster a verterbrate

Answer 1

Short answer is no!

Vertebrates - animals with backbones - are a subset of the chordates (animals with a stiff rod along the back), and include fish, amphibians, reptiles, birds and mammals. All other multicelled animals, including lobsters, are invertebrates, including lobsters. Lobsters are arthropods, a large and complex invertebrate group that includes insects, Spiders, crustaceans (crabs, lobsters, shrimps, woodlice, ...) and other animals that are characterised by jointed legs and a hard exoskeleton (external skeleton, a bit like a suit of armour). Like other such animals, lobsters need to shed the exoskeleton periodically in order to grow. A new, larger exoskeleton is formed on the outside, which at first is soft and then quickly hardens. Vertebrates, which include me and you, can just grow without such moulting - their skeleton is inside, and grows continuously (as opposed to in stages), until any maximum size is reached.