Japanese mantis shrimp
Squillidae - Oratosquilla oratoria

What does it look like?

The Japanese mantis shrimp are light grey and can grow up to 185mm long (18.5cm). It has two spiny claws to capture food. Japanese mantis shrimp can easily be confused with a native species that is of similar size and colour. However, Japanese mantis shrimp has red-maroon ridges running down the mid-length of its body and the outer surface of the tail fan is blue and yellow (it is grey and yellow in the native species).

Japanese mantis shrimp live in burrows in soft sediments, sand and mud in sheltered bays and estuaries. It is native to the north-western Pacific where it is most common in temperate waters of China and Japan.

Why is it a problem?

The Japanese mantis shrimp preys on shrimps, crabs and thin-shelled molluscs and can alter habitats through its burrowing activities. When abundant, they can play a role in structuring benthic communities and may compete for food and space with other crustaceans.

In its native range, Japanese mantis shrimps live for 3 to 3.5 years. Males attained sexual maturity at 4-5 cm body length and females at 7 cm. Females can brood a maximum of 50,000 eggs and remain in their burrows when caring for the embryos. After hatching, larvae pass through several free-swimming stages, with an estimated larval life of around 2 months.

Control Methods

You must notify the Northland Regional Council if you think you have seen this pest outside of Kaipara Harbour.

You can help prevent the spread of marine pests by:

• Regularly cleaning your boat’s hull – ideally keep fouling growth to no more than a light slime layer.

• Applying a thorough coating of antifouling paint and keep it in good condition.

• Ensure your hull is clean and free of fouling before you travel to a new area.

• Clean and dry any marine equipment (e.g. ropes, lines and pots) before using in a new area.

• Inspect areas on your boat that retain water for signs of marine life.

• Check for aquatic weeds tangled around anchors, trailers and other equipment.


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