Invertabrates

Jellyfish are common forms of invertabrates and can move freely, their tentacles are an adaptation that they use to protect themselves.

An invrtabrate is considered a species that is a multi-cellular and eukaryotic animal. A mass majority of animals, about 97% that make up all known animal species are invertabrates. Invertabrates are said to have a common eukaryotic form of ancestor and this can be recognized with similarities to past fossils found through invertabrate palaeontology. Forms of invertabrates are sponges, jellyfish and other fish along with many, many other species. A common importance for these invertabrates is that because they have no spinal chord they often protect themselves by having a form of shell or hard exoskeleton but that isn't always the case. In the childrens cartoon "Spongebob Squarepants" it displays the nautical adventures of a common seasponge and often they display how Spongebob doesn't have a vertabrate giving him body capabilities that most creatures such as humans do not possess like bending or stretching in weird ways.

Sources:
Mrs. Beethe's notes.