Were jellyfish and worms the first animals???

[edit] Timeline

Period Animals Year

Precambrian Jellyfish, Worms 3500 mya (mya - million year ago)

Cambrian Sellfish, corals, jawless fish 570 mya

Ordovician 505 mya

Silurian First land plants 438 mya

Devonian Insects, spiders 408 mya

Carboniferous First reptile 360 mya

Permian 286 mya

Triassic Dinosaurs, mammals, frogs 245 mya

Jurassic First birds 208 mya

Cretaceous Snakes, first mordern animals 144 mya

Palaeocene Owls, shrews 65 mya

Eocene Horses, dogs, cats, elephants, rabbit 58 mya

Oligocene Deer, pigs, monkeys, rhino 37 mya

Miocene Mice, rats, apes 24 mya

Pliocene Cattle, sheep 5 mya

Pleistocene (ice age) Homo sapien 2 million years ago







from wikipedia

Were jellyfish and worms the first animals???
This is a very interesting question. No one knows the answer to this since there are no fossils to guide us. However, it seems that the earliest multicellular animals were probably somewhat like "Hydra", which are the earliest animals that share Hox genes with us. These animals were likely to be free swimming and having only one "hole" that served as both mouth and anus. Subsequently these creatures evolved into Jellyfish-like creatures and then later to worm-like creatures, which became eel-like creatures, then shark-like creatures, etc, etc.The embryologic remnant of this hole is likely to be your belly button. If you are further interested in this subject, I highly recommend the book "The Ancestor's Tale" by Richard Dawkins.