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🧬 Biological Classification (Kingdom to Species)Cambaroides japonicus

Kingdom

Animalia

Phylum

Arthropoda

Class

Malacostraca

Order

Decapoda

Family

Cambaroididae

Genus

Cambaroides

Species

Cambaroides japonicus

Malacostraca🍂 Omnivore

Japanese crayfish

Cambaroides japonicus (Japanese crayfish · ニホンザリガニ)

🛡️ Conservation Status (IUCN Red List)DD (Data Deficient)

DDData Deficient

LCLeast Concern

NTNear Threatened

VUVulnerable

ENEndangered

CRCritically End.

EWExtinct in Wild

EXExtinct

Geological Era

Extant

Diet

Omnivore

Length · Height

5~7cm · No data

Mass · Top Speed

No data · No data

Habitat & Fossil Locality

Cold, clear headwaters, springs, and mountain lakes at water temperatures of 20°C or below in Hokkaido and northern Tohoku, Japan

💡 Everyday Comparisons for Size, Mass & Speed

💡 Its adult body length of 5–7 cm is slightly shorter than the long side of a credit card (about 8.6 cm) (Comparison).
💡 Information from Sapporo Maruyama Zoo notes that it was assessed as Vulnerable (VU, 2000) on the Japanese Ministry of the Environment Red List and designated a National Rare Species of Wild Fauna and Flora in January 2023. Because it has been confirmed to die from a water mold carried by the invasive crayfish Uchida-gajae (a Korean animal name), it is a representative case of native crayfish being threatened by the spread of invasive crayfish.

Reference standards: coach bus ~12 m, mid-size car ~4.9 m, compact car ~1 t, basketball hoop 3.05 m, credit card 8.56 cm.

#일본가재#Cambaroides japonicus

📖 1. Overview

The Japanese crayfish is the only native crayfish endemic to Japan, living in cold, clear waters across all of Hokkaido and northern Aomori, Akita, and Iwate. The IUCN Red List assessed it as Data Deficient (DD) in 2010.

🦴 2. Anatomy & Morphology

Adults are 5–7 cm long and brown. Its claws and head lack spines, and the rostrum is a short triangle.

🔍 3. Ecology & Behavior

It is omnivorous, eating insects and organic matter centered on fallen leaves, and spends its whole life in freshwater without moving far. It takes 5 years to reach breeding age; it mates in autumn, lays 40–60 eggs in spring to carry under its abdomen, and hatches them in mid- to late June. Its lifespan is about 10 years.