[5] Like other horseshoe crabs, the carapace of T. tridentatus consists of a larger frontal one (the prosoma) and a smaller, spine-edged rear one (the opisthosoma).

[10] Like other species of horseshoe crabs, T. tridentatus is an omnivore and feeds on molluscs, worms, other benthic invertebrates and algae.

[5] Large batches of eggs are laid in holes dug in sandy beaches in special nursery areas off the coast.

Adults move offshore for the winter, hibernating buried in the seabed at depths of around 20 metres (66 ft), coming inshore again when the water warms up the following year.

As a poikilotherm, this horseshoe crab is much affected by rising seawater temperatures, reacting by burying itself deeply in the sediment and sometimes going into diapause.

[11] The tri-spine horseshoe crab is at risk from over-fishing, pollution and the loss of their breeding grounds.

As of 2019, the International Union for Conservation of Nature classifies the species as "Endangered" based on recent population and habitat declines.