Crustacean larvae are subject to predation by a diverse assemblage of invertebrate and vertebrate predators. These predators can find larval prey through visual, tactile, or chemical means and then capture larvae with feeding currents, grasping appendages, suction, or filtering sieves. In response to this predation, crustacean larvae have evolved extensive morphological defenses such as long spines and hard chitinous carapaces. They also exhibit sophisticated behaviors, including extensive vertical and horizontal migrations to avoid encountering predators, rapid darting to evade attacks by nearby predators, and strong swimming to escape after an attack by a predator. Chemical defenses have not yet been documented in crustacean larvae. Interspecific differences in defensive capabilities can be profound, including crab zoeae with spines zero to seven times their body length, and copepod nauplii with dichotomous swimming behaviors that trade off detectability by predators with escape ability. Our review of the literature on predator gut contents and lab feeding experiments found that crustacean larvae are consumed by a vast diversity of predators of all feeding types. These include gray whales, fishes, ascidians, bivalves, octopus larvae, cnidarians, insects, and numerous other crustaceans. Crustacean larvae are important components of many predators’ diets, and the primary food for others, including larvae of commercially important species such as cod. Future research on chemical defenses and phenotypic plasticity are needed to fill gaps in our knowledge of crustacean larval defenses. The predatory threats faced by crustacean larvae and their defensive adaptations have important implications for our understanding of the evolution of larval forms in Crustacea and the factors determining crustacean abundance and distribution.