Alpheus heterochaelis

Alpheus heterochaelis, called the bigclaw snapping shrimp, belongs to the Alpheidae family of snapper or pistol shrimp. It lives in the western Atlantic Ocean and the Gulf of Mexico.

This shrimp has a small rostrum and no spines along the edge of its carapace. Its oversized claw—which can be either the right or left one—gives the species its common name and measures half the length of its body. Below the finger joint, each side of this claw has a deep notch. The other claw is normal-sized and unmodified. Within its range, it is the largest snapping shrimp, reaching up to 5.5 centimeters (2.2 inches) long, though most adults are much smaller. Its body is a translucent dark green, with orange and blue tips on the uropods.

The species occurs in tropical and semitropical waters of the Gulf of Mexico, the West Indies, Bermuda, and the western Atlantic from Cape Hatteras south to Florida and Brazil. It stays near the seabed in shallow areas, favoring reefs, seagrass meadows, salt marshes, and muddy spots. During the day it often hides in natural openings, though it is not clear if it can dig its own burrow.

The bigclaw snapping shrimp makes a loud, staccato noise by snapping its big claw shut very fast, which shoots out a high-speed jet of water. This creates a tiny, short-lived cavitation bubble, and the sound comes from that bubble collapsing instantly. A spark also forms at the same time. The snap helps scare off predators, stun prey, and is used for display. How long the shrimp keeps its claw cocked does not change how far the stun travels; there is a maximum distance, and cocking beyond that point has no extra effect.

It eats worms, small crustaceans, and fish like gobies and pearlfish. Weakfish (Cynoscion regalis) prey on it. The shrimp often shares burrows with the black-clawed mud crab (Panopeus herbstii) without being eaten, even though that crab eats other shrimp of similar size. Bigclaw snapping shrimp usually live in monogamous pairs. The female is only receptive for a short time right after molting. Eggs hatch about four weeks after being laid, and the larvae do not feed, relying on their egg yolks. They develop quickly, passing through three larval stages in about five days. Newly metamorphosed juveniles have equal-sized claws; one claw enlarges later.