Seabob Shrimp. The seabob shrimp is a decapod crustacean in the Western Atlantic. The species is typically found on mud or sand substrates in both marine and brackish waters, with adults reportedly able to tolerate fresher water than most penaeid shrimps, with high abundance often being associated with areas of river run-off, such as seaward of estuary mouths. The species is a relatively fast growing species, growing to a maximum of around 140mm although typical adult sizes are considerably smaller (with females significantly larger than males). Typical lifespan for the species is around 18 months with maturity being reached relatively quickly, at around 24mm (carapace length) for females.