Colorful clownfish swim among an array of sea anemones. Anemones appear in an enchanting variety of shapes and colors, but these simple invertebrates are essentially tubelike animals. One end of an anemone’s body is attached to or dug into the seafloor, while the other hosts a mouth surrounded by tentacles.
Photograph by Darlyne A. Murawski, National Geographic
Some anemones piggyback on the shells of hermit crabs. The maneuver is mutually beneficial: The anemones get a mobile, competition-free surface on which to perch and pick up scraps, and the crabs get an effective camouflage and protection provided by the sea anemone’s toxic tentacles.
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