sand flea

from The American Heritage® Dictionary of the English Language, 5th Edition.

• noun Any of various small crustaceans living on sandy beaches, such as a beach flea.

from The Century Dictionary.

• noun The chigoe or jigger, Sarcopsylla penetrans.
• noun A sand-hopper or beach-flea; one of numerous small amphipod crustaceans which hop like fleas on the seashore.

from Wiktionary, Creative Commons Attribution/Share-Alike License.

• noun Any of various small crustaceans of the order Amphipoda, that are found on beaches and jump like a flea.
• noun A small tropical flea, Tunga penetrans; a chigoe.

from WordNet 3.0 Copyright 2006 by Princeton University. All rights reserved.

• noun small amphipod crustaceans that hop like fleas; common on ocean beaches