In the "World's Oceans" area, the "Deep Sea Creatures 1" tank primarily displays invertebrates that inhabit the deep sea, such as the bird's foot, the mussel clam, and the hermit crab.

This time, we'll introduce the hermit crab, Jingoro, which has an orange body and carries a distinctive "shell (*)" on its back.

*Hermit crab: The shell that hermit crabs carry on their backs.


Jingoro hermit crab
The Jingoro hermit crab is a species of hermit crab endemic to Japan, inhabiting sandy and muddy bottoms at depths of 90 to 400 meters in the waters from Sagami Bay to Hyuga-nada. It grows to a length of about 8 cm and primarily uses the shells of gastropods, such as the Ebisu-gai species, as its home.

As shown in the photo above, the hermit crab attaches a sea anemone to the shell it uses as its home. Because the sea anemone has venomous stinging cells, the hermit crab can protect itself from predators such as octopuses, and the sea anemone can get some of the hermit crab's leftover food and is carried by the hermit crab without having to move itself. In other words, it is a mutually beneficial relationship.

Furthermore, it is known that as hermit crabs grow, they not only move to larger shells to accommodate their bodies, but also move their anemones to the new shells. However, some species of anemones that attach to the shells of the hermit crab, such as the dwarf golden anemone, secrete fluids that enlarge the shells, so sometimes the hermit crab doesn't need to move once it has grown larger.

An anemone of an unknown species is attached to the shell of a hermit crab, which is on display at the aquarium.

When feeding the hermit crabs, I use a special stick to directly feed them sakura shrimp to avoid any leftovers, or I scatter a small amount of minced sakura shrimp or polychaete worms on the bottom of the tank so that they can eat it all. As a result, I also feed the anemones sakura shrimp directly so that they don't get weak from not having enough food.


Feeding scene
The deep-sea tanks are dimly lit to be considerate of the creatures, so it might be a little difficult to spot them, but try to find the hermit crabs and sea anemones and observe how they live together in symbiosis.

[Tokyo Sea Life Park]

(July 15, 2022)