Juvenile horseshoe crab behaviour – self righting

This post documents the behaviour of a juvenile horseshoe crab (Carcinoscorpius rotundicauda) at an inter-tidal mudflat at Luk Geng, New Territories, Hong Kong.

This photograph was taken just as the tide was receding and shows a juvenile C. rotundicauda on its back trying to self-right itself using its tail. The tail marks left by the animal’s actions can clearly be seen in the muddy substrate (if horseshoe crabs end up on their backs, they use their tail as a lever to self-right themselves).

Juvenile horseshoe crab behaviour - burrowing

This post documents the behaviour of juvenile horseshoe crabs (Tachypleus tridentatus) based on observations made at an inter-tidal mudflat at Ha Pak Nai, Deep Bay, New Territories, Hong Kong.

All observable juvenile horseshoe crab activity on the mudflat appears to be synchronized with the tides. When the tide comes in, the juveniles bury themselves in the substrate. When the tide recedes, they emerge to forage.

The following photographs show two instances of juvenile T. tridentatus burrowing on the exposed mudflat:

Burrowing 1

Juvenile T. tridentatus sprints across the mudflat, then burrows into the sandy substrate.

Burrowing 2

Juvenile T. tridentatus burrowing into sandy substrate

Comment

Understanding the way that tidal cycles dictate the foraging and burrowing activities of juvenile horseshoe crabs may help in the interpretation of the palaeo-environment of other localities with horseshoe crab fossils, such as Mazon Creek.

Juvenile horseshoe crab behaviour – walking, wandering and sprinting

This post documents the behaviour of juvenile horseshoe crabs (Tachypleus tridentatus) based on observations made at an inter-tidal mudflat at Ha Pak Nai, Deep Bay, New Territories, Hong Kong.

All observable juvenile horseshoe crab activity on the mudflat appears to be synchronized with the tides. Before the tide comes in, the juveniles bury themselves in the substrate. When the tide recedes, they emerge to forage.

The following are examples of walking, wandering and sprinting behaviour, either after the tide has receded, or after foraging activity has taken place.

Wandering as the tide is receding

This video is of a juvenile T. tridentatus wandering from pool to pool in a well developed seagrass bed, just as the tide is receding, perhaps searching for a new foraging area:

http://www.youtube.com/watch?v=CKdfHu1Wjas

Olympic sprint

These photographs show a juvenile T. tridentatus running at high speed across an exposed area of mudflat and quickly burying itself:

Transition from foraging to walking

The following series of photographs shows the sequence of trails left by a juvenile T. tridentatus as it transitions from foraging to walking:

Pool on sandy area of beach where the photographs below were taken.

Foraging horseshoe crab(s)

Transition from foraging to walking trail (walking starts with tail marks)

Walking horseshoe crab