THE ANIMAL FILES

Japanese spider crab

Macrocheira kaempferi

Long legs are not the same measurement as a wide body.

Japanese spider crabs have long slender limbs around a much more compact central body. Adults live on the seabed, while newly hatched larvae drift near the surface. Their diet includes plant material, animals and scavenged food.[1]

Follow the evidence ↓
Japanese spider crab
Image: Lycaon (Hans Hillewaert) · Commons · CC BY 2.5
Body and span
Limb span differs from carapace width.[1]
A drifting beginning
Females carry eggs before larvae hatch.[1]
A varied seabed menu
Scavenging supplements other feeding.[1]

Body and span

The orange body and white-spotted legs give a striking outline. Males have longer claw-bearing limbs than females. Comparing span with body width mixes different measurements, and a wide silhouette does not mean the central shell occupies that whole space.[1]

A drifting beginning

Eggs remain attached to abdominal appendages until hatching. Tiny planktonic larvae then pass through zoeal and megalopa stages before young crabs develop. Near-surface currents influence that early journey, contrasting with the deeper seabed used by adults.[1]

A varied seabed menu

The diet includes plant material, small marine animals and decaying fish. Claws can open mollusc shells, while dead food is scavenged from the seabed.[1]

A COMMON MIX-UP

Does a giant leg span equal the width of the crab's body?

No. Span includes extended limbs, while carapace width measures the central shell.[1]

TRY A LITTLE REASONING

Why could a surface-current model matter to a crab found deep on the seabed?

Reveal the explanation

Its planktonic larvae occupy near-surface water before settling, so currents affect the early life stage.[1]

Sources & editorial notes

Adapted and translated from the cited Wikipedia revisions, with source-linked reasoning. Image credit and licence are listed separately above.

Adapted and translated from Wikipedia contributors; exact revisions are linked below. CC BY-SA 4.0

  1. Wikipedia contributors — Japanese spider crab (cited revision)
  2. NCBI Taxonomy — Macrocheira kaempferi

Last fact check:

One discovery leads to another

European green crabA green crab can be red—and still be the same species.Carcinus maenas ↗Atlantic blue crabAn estuary resident with an ocean-going beginning.Callinectes sapidus ↗Chinese mitten crabA freshwater feeding life leads downstream to breeding.Eriocheir sinensis ↗