Extracellular vs. Intracellular Digestion: A Phyla-by-Phyla Guide

Extracellular digestion:

- Cnidaria (e.g. jellyfish)

- Platyhelminthes (e.g. flatworms)

- Nematoda (e.g. roundworms)

- Rotifera (e.g. rotifers)

Intracellular digestion:

- Porifera (e.g. sponges)

- Ctenophora (e.g. comb jellies)

- Mollusca (e.g. clams, snails, octopuses)

- Annelida (e.g. earthworms, leeches)

- Arthropoda (e.g. insects, spiders, crustaceans)

Note that some animals, such as the starfish, use a combination of both extra and intra-cellular digestion.