Jassa falcata is a tube-dwelling amphipod. It is commonly know as a scud.

The scud is one of the thousands of species of amphopod. Like lobsters, crabs and shrimps, amphopods are crustaceans in the class Malacostraca.

The scud (Jassa falcata) constructs tubes of debris. It's a fouling organism. It grows on the bottom of ships and slows them down. Jassa falcata forms dense mats or nests. The male and the female live in different tubes. Jassa falcata feeds generally on hydroid growth on the bottom of rafts and ships. It's generally a suspension feeder normally found on sediment areas.

Males are 7-13 millimeters and females are 6-12 millimeters. Colors vary yellow-gray with brown red or black patches depending on the color of the habitat. Each Jassa falcata has two antennae. Antennae 1 has two segmented flagella and is shorter and more slender than antennae 2.