Northern Shrimp

• It is a protandrous hermaphrodite: every individual is born and first breeds as a male, and after a few years turns into a female.
• The female carries the eggs attached beneath her abdomen for several months before they hatch.
• Water temperature determines the age at which they change sex, so the warming of the sea alters the structure of the population.
• It is a protandrous hermaphrodite: all are born male, breed as such and at around two and a half years old their testes turn into ovaries and they end their lives as females.
• The transition runs through seven stages with visible changes in the pleopods and the sternal spines.
• That is why the females are much larger than the males: males are around 12 cm and females reach 18.
• The size at which they change sex is not fixed. In two Icelandic populations whose biomass collapsed after 2000, the change began happening at smaller sizes, which suggests population density plays a part.
• That makes sex-changing populations more sensitive to fishing pressure and means they cannot be managed like the rest.

Skeleton type

Invertebrate - articulated calcareous exoskeleton (crustacean)

Habitat and environment

Cold muddy bottoms of the North Atlantic and the Arctic, from 20 to 1,300 m

Gestation / incubation

The female carries the eggs for about 164 days

Litter / clutch size

From 600 to 4,900 eggs per female, about 2,000 on average

Sources consulted: Wikipedia (es): Pandalus borealis · ScienceDirect (Hughes 1989) · Science Advances, How colonial animals evolve · Wikipedia, Zooid