1. Size and Shape of Abdominal Segments:
- Male hermit crabs have narrower and longer abdominal segments compared to females.
- Female hermit crabs have wider and more rounded abdominal segments to accommodate the space required for carrying and protecting eggs.
2. Gonopores:
- Male hermit crabs have a pair of gonopores located on the second pair of abdominal segments (counting from the tail end).
- Female hermit crabs have a single gonopore located in the middle of the third pair of abdominal segments.
The gonopores are used by both sexes for releasing reproductive fluids during mating.
3. Pleon Openings (Coxopods):
- Male hermit crabs have a small opening called the coxal opening on the underside of the penultimate (second-to-last) pair of walking legs.
- Female hermit crabs do not have coxal openings.
Coxal openings are used by males for clasping during reproduction and for transferring sperm to females.
4. Uropods:
- In some hermit crab species, mature males have more noticeably enlarged uropods (appendages on the tail fan) compared to females.
It's important to note that these are general guidelines and can vary among different hermit crab species. If you are unsure, it's best to consult a knowledgeable source or an expert in hermit crab biology.