Beach Hoppers Don't Just
Hop Beaches

Some things are so typical of the California shore that people tend to simply take them for granted - the sun, the waves, wind, sand, the kelp washed ashore, and beach hoppers.

Beach hoppers? Of course. Just about everyone has seen these little critters that, true to their name, hop around on the beach. More typically called "amphipods," they are an order of crustaceans that have both of the typical crustacean appendages, or those for both walking and hopping ("ampho" being Greek for "both" and "poda" for "foot"). But easier than looking at their feet, an easier way to distinguish amphipods from other related crustaceans, such as isopods, is that amphipods appear to be flattened from side-to-side, where as isopods are usually flat from top-to-bottom.

Worldwide there are over 5,000 types of amphipods to be found, and some California beaches alone are home to over 100 species! Those common ones, which are such a part of the California beach scene, are often called "sand fleas." But don't worry - they don't bite. These multi-members of the genera Orchestoides, Orchestia and related species can reach an inch in length, so it is a good thing that they don't bite, especially not a bite that would be in proportion to their size in relation to real insect fleas!

The most interesting beach hoppers, however, don't hop beaches. These are the amphipods that dwell in deeper waters, such as the dove snail mimic (Pleustes platypa). It grows to about a quarter inch long and is found on giant bladder kelp (Macrocystis pyrifera). Its color is quite distinct for an amphipod, being golden brown with both dark red and light yellow bands. But this makes it almost identical to the carnated dove snail (Mitrella carinata), which lives nearby on the same kelp.

The giant amphipod (Cymadusa uncinata) is also a giant bladder kelp dweller, but it hides itself in another way. This 1 1/2 inch long creature takes on the leaf-like blades of its kelp home and rolls it up into a tube, gluing the edges together to make a cozy little abode.

Down below giant bladder kelp resides the tunicate amphipod (Polycheria osborni). It makes its hiding place by slowly scootching itself in backwards into the soft flesh of the sea pork tunicate (Aplidium californicum). From its protective hole, it is able to stick its antennae and feet up into the water and filter out its food. In effect, then, this amphipod functions in the same way as does another familiar group of crustaceans, namely barnacles, but without the benefit of their hard outer shell.

The mussel hopper (Elasmophus rapax) is a wide-ranging California amphipod. Mussels are so abundant along the rocky shore and on the artificial ecosystems of pier piling and oil platforms, and yet it is figured that there are just about as many mussel hoppers in any mussel bed as there are mussels themselves.

There are lots of other intriguing amphipods that are found in California's waters. Allogaussia recondita hangs out with impunity in the gullet of the aggregate sea anemone (Anthopleura eleantissima), a manner reminiscent to tropical clownfishes. Photis conchincola is a real hermit crab "wannabe" which emulates the larger crustacean's habit of adorning itself with a seashell mobile home. Plus there is Heterophlias seclusus, a sand dweller, which is considered to be an odd-ball among amphipods because of being flattened from top to bottom - to say nothing of it resembling a miniature cross between an armored tank and an ankylo-saurus dinosaur!

Amphipods are mainly intertidal and subtidal, but there are some that live in the depths of the ocean and also some that are to be found in freshwater. There are even a few terrestrial species, which are often called leafmold hoppers. None of the terrestrial amphipods, though, are native to California. There aren't any that are native to even North America. Nevertheless, some Southern Hemisphere species, such as Talitrus sylvanicus have made their way into garden hot houses in the state.

While the better-known amphipods are easy to find, as a whole, amphipods tend to be an extremely complicated group of animals to classify, even for the experts. But it takes no expert to recognize that amphipods are a fascinating group of little critters that can easily be observed by all.