Date: 8 October 2013
Location: Ha Pak Nai, Deep Bay, Hong Kong.
Comment: Mating pair of Tachypleus
tridentatus caught by a local fisherman close to the shore at Ha Pak Nai,
Deep Bay, Hong Kong.
Female: 33 cms across prosoma. 67 cms long.
Male: 25 cms across prosoma. Length not measured because of broken tail.
Female: 33 cms across prosoma. 67 cms long.
Male: 25 cms across prosoma. Length not measured because of broken tail.
The fisherman donated the pair to the horseshoe crab breed
and release programme being run by City University and Ocean Park in Hong Kong.
This is them in their new home.
Male and female together
Male on the right.
Female
In T. tridentatus,
sexual dimorphism is shown by the presence of notches on the anterior margin of
the male prosoma (head shield) and these are a secondary sexual characteristic –
they are not apparent in the juveniles. These notches assist the male in attaching
to the female during mating and are only present in male T. tridentatus – this is one of the distinguishing features of the
male of this species.
The scars on the female opisthoma caused by prolonged
attachment of the male. This female was carrying no eggs, suggesting this
marked the end of a successful spawning season for the pair.
