Hemigrapsus nudus

The purple shore crab is a common crab of the family Varunidae that is indigenous to the west coast of United States, Canada, and Mexico. H. nudus was first described in 1847 by Adam White, and in 1851, James Dwight Dana formally classified the species. H. nudus is a small, amphibious crab that is similar physically and behaviorally to Pachygrapsus crassipes and Hemigrapsus oregonensis. The purple shore crab is generally a dark purple color with olive green, red, and white spots. Mating season for H. nudus begins in mid-winter and larval crabs undergo 5 zoeal stages and a juvenile stage. Adult crabs mainly feed on algae but will occasionally scavenge other animals. H. nudus prefers inter-tidal and sub-tidal zones, and it can oftentimes be found sheltering under rocks or other debris. H. nudus demonstrates complex compensatory mechanisms to counteract fluctuating salinity and water oxygen concentrations, permitting it to live in a variety of different environments.

Hemigrapsus nudus

Walter Siegmund (talk) · CC BY-SA 3.0 · via Wikipedia/Commons. May be a photograph of a specimen, or an artist’s reconstruction — an interpretation of a skeleton, since colour and soft tissue are almost never preserved.

On record

Recorded, not inferred
Also called
purple shore crabPBDB
Sits inside
HemigrapsusPBDB
Diet
detritivorePBDB, for Grapsoidea
Life habit
infaunalPBDB, for Varunidae
Motility
actively mobilePBDB, for Malacostraca
Vision
well-developedPBDB, for Malacostraca

Time the record covers

At most 2.6 million years on record.

Every occurrence read is dated to somewhere between 2.58 Mya and 0 Mya, and nothing in the dating separates them, so that window is what the record shows rather than a span.

Pliocene — about 0 of 5 occurrencesPleistocene — about 5 of 5 occurrencesPleistoceneHolocene — about 0 of 5 occurrences2.7–2.6 Mya — about 0.0 occurrences2.6–2.5 Mya — about 0.1 occurrences2.5–2.4 Mya — about 0.1 occurrences2.4–2.3 Mya — about 0.1 occurrences2.3–2.2 Mya — about 0.1 occurrences2.2–2.1 Mya — about 0.1 occurrences2.1–2.0 Mya — about 0.1 occurrences2.0–1.8 Mya — about 0.1 occurrences1.8–1.7 Mya — about 0.1 occurrences1.7–1.6 Mya — about 0.1 occurrences1.6–1.5 Mya — about 0.1 occurrences1.5–1.4 Mya — about 0.1 occurrences1.4–1.3 Mya — about 0.1 occurrences1.3–1.2 Mya — about 0.1 occurrences1.2–1.1 Mya — about 0.1 occurrences1.1–1.0 Mya — about 0.1 occurrences1.0–924 ka Mya — about 0.1 occurrences924 ka–821 ka Mya — about 0.1 occurrences821 ka–719 ka Mya — about 0.2 occurrences719 ka–616 ka Mya — about 0.3 occurrences616 ka–513 ka Mya — about 0.3 occurrences513 ka–411 ka Mya — about 0.3 occurrences411 ka–308 ka Mya — about 0.3 occurrences308 ka–205 ka Mya — about 0.3 occurrences205 ka–103 ka Mya — about 0.5 occurrences103 ka–0 Mya — about 0.9 occurrences3.08 Mya0 Mya

5 occurrences of Hemigrapsus nudus on record, most of them in the Pleistocene. The Paleobiology Database records this as a living group. Bar height is expected occurrences, not a count: each fossil is spread across the span it is dated to, so a tall narrow bar means tight dating and a low wide one means loose.

When

5 occurrences

These are dates about fossils, not the animal: the record can only begin after it arose and end before it died out, so either end may reach further. Shares are expected occurrences: a fossil dated to a span is counted partly in each period it straddles. More on what this infers.

Found in

3 formations

San Pedro — 33.80°N, 118.17°WSan Pedro — 32.67°N, 117.14°WSan Pedro Sand — 33.74°N, 118.28°WPalos Verdes Sand — 33.60°N, 117.88°W

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The named rock units Hemigrapsus nudus has been recovered from, largest first. Drawn where the rock is now, not where it formed. 1 occurrence has no formation on record, which is common for older literature.

Hemigrapsus nudus and its relatives

Pleistocene

Where Hemigrapsus nudus and its relatives were recorded in the Pleistocene.

Found in the same rock

631 taxa

The Paleobiology Database records 4 sites for Hemigrapsus nudus, and this reads all of them. The number is how many of those sites it was catalogued from too. The 24 sharing the most are listed.

This is not a list of everything alive at the time. It is only what has come out of the same ground as this animal and been written down.

Entered from

2 references

Each of the 5 occurrences read was entered from one of these publications, ordered by how many each accounts for. This is not a search for papers mentioning the name. Each entry links to doi.org. Relayed as the Paleobiology Database holds them, not checked against what they resolve to.

Media and terms

Media content1

Picture of Hemigrapsus nudus

Credit
Walter Siegmund (talk)
Licence
CC BY-SA 3.0
Commercial use
the licence allows it

No 3D scan of Hemigrapsus nudus was found in MorphoSource and Sketchfab.

Smithsonian Open Access was not reached for this taxon, so this list is what the others held rather than everything there is.

The description on this site

Licence
CC BY-SA 4.0

This is what the site found, which is not the same as what exists.

Keep going

What may have been alongside itHemigrapsus through timeFormations of the PleistoceneThe world it lived on

Occurrence data from the Paleobiology Database, CC BY 4.0. (Dana 1851)