Sexual dimorphism and reproductive strategy of the kelp-dwelling isopod Amphoroidea typa (Isopoda, Sphaeromatidae)

What is it about?

This study documents important aspects of the life history of an isopod that inhabits large kelp species from the Chilean coast. The results show that in this isopod species, Amphoroidea typa, the females are larger than males. Only the largest females were incubating offspring, suggesting that they only produce one brood during their life. The frequencies of injuries is high indicating that these isopods are exposed to high predation pressure. Cryptic coloration is interpreted as camouflage on the kelps reducing the probability to be detected by predators. Several other species from the isopod family Sphaeromatidae also have a semelparous reproductive strategy (females produce only one brood), but there is no clear relationship with body size or life style (in burrows or free-living), suggesting that the evolution of semelparity is variable, depending on the prevailing environmental conditions.

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