Figure 6.Ericthonius pugnax (Dana, 1853), male, (UKMMZ-1136), 3.8 mm. Pulau Tioman, South China Sea. Scale for G2 ♂ represents 0.6 mm; A1, A2 HD and ABD scales = 0.5 mm, G1 ♂ scale = 0.25 mm; P5 scale = 0.2 mm.
These are tube dwelling, nonnative amphipods introduced into harbors by shipping. Adult males, such as this one, leave the safety of their tube to cruise about in search of a receptive female.