![How male pea crabs might find females using pheromones](http://static.sciencelearn.org.nz/images/images/000/000/848/full/how_male_pea_crabs_might_find_females_oversize20160302-30978-1jcxqil.jpg?1674165058)
Male pea crabs need to work out which mussels contain females so they can avoid getting crushed by a closing mussel shell while searching for a mate. It is likely that males detect a pheromone that is released by females who are ready to mate. This chemical signal would guide the male crab to a mussel that contains a female.