Xenophyophores are giant unicellular organisms found throughout the world's oceans. They can be 20 centimeters in diameter.

Some of the major phyla in the animal kingdom include Porifera (sponges), Cnidaria (jellyfish, corals), Platyhelminthes (flatworms), Annelida (segmented worms), Mollusca (snails, clams), Arthropoda (insects, spiders), Echinodermata (starfish, sea urchins), and Chordata (vertebrates and close relatives).

There are far too many invertebrate species to list. Note that there are far more invertebrate species than vertebrate species. However, I here are a list of invertebrate phyla:

Acanthocephala (a phylum of worm)

Acoelomorpha (a phylum of worm)

Annelida (a phylum of worm)

Arthropoda (spiders, crabs, etc)

Brachiopoda

Bryozoa

Chaetognatha (a phylum of worm)

Cnidaria (corals, sea anemones, jellyfish, etc)

Ctenophora (comb jellies)

Cycliophora

Echinodermata (sea urchins, starfish, etc)

Echiura (a phylum of worm)

Entoprocta (a phylum of worm)

Gastrotricha

Gnathostomulida (a phylum of worm)

Hemichordata (a phylum of worm)

Kinorhyncha

Loricifera

Micrognathozoa

Mollusca (octopi, clams, etc)

Nematoda (a phylum of worm)

Nematomorpha (a phylum of worm)

Nemertea (a phylum of worm)

Onychophora (a phylum of worm)

Orthonectida

Phoronida (a phylum of worm)

Placozoa

Platyhelminthes (flat worms)

Porifera (sponges)

Priapulida

Rhombozoa

Rotifera

Sipuncula

Tardigrada (Water bears, which are microscopic animals that live in and eat moss. They look like caterpillars).

Xenoturbellida (strange flatworm)