Porifera (the sponges), Bryozoan (sea mats), Cnidaria (hydroids, sea firs, jellyfish, anemones) and others.

In the tidal sea caves of Gower and Pembroke there lives a variety of organisms. Living on the walls you may find sponges (a difficult group to identify), sea firs, sea anemones, sea mats, and an unusual chordate - the sea squirt. Crawling in search of food are starfish, crabs, sea urchins, molluscs and swimming around there are fish and jellyfish. Seaweed (species of algae), needs light for photosynthesis and so will only be found near the entrance. Different colour seaweeds have different photosynthetic pigments allowing them to live at different depths in the sea (in order of descending light intensity: green, brown, red seaweed).

Barnacles, sponge (orange) and a sea anemone (dark red) in threshold of sea cave on Gower. These are all animals.

There are probably sponges and relatives of the sea mats living in the inland caves but none have yet been reported.

Fossil corals

In the cave you may see the ancestors of some of these creatures as fossils. The tubes of fossil coral will look like tubes or circles depending on which angle they are viewed from. Over hundreds of thousands of years the dominant creatures changed due to changing sea conditions and evolution. Some of the fossils are so abundant that geologists use particular species to help identify a particular band of limestone. Corals are especially useful and include Dibunophyllum, Seminula and Zaphrentis.