Identification Guide to Marine Invertebrates of Texas by Brenda Bowling Texas Parks and Wildlife Department April 12, 2019 Version 4 Page 1 Marine Crabs of Texas Mole crab Yellow box crab Giant hermit Surf hermit Lepidopa benedicti Calappa sulcata Petrochirus diogenes Isocheles wurdemanni Family Albuneidae Family Calappidae Family Diogenidae Family Diogenidae Blue-spot hermit Thinstripe hermit Blue land crab Flecked box crab Paguristes hummi Clibanarius vittatus Cardisoma guanhumi Hepatus pudibundus Family Diogenidae Family Diogenidae Family Gecarcinidae Family Hepatidae Calico box crab Puerto Rican sand crab False arrow crab Pink purse crab Hepatus epheliticus Emerita portoricensis Metoporhaphis calcarata Persephona crinita Family Hepatidae Family Hippidae Family Inachidae Family Leucosiidae Mottled purse crab Stone crab Red-jointed fiddler crab Atlantic ghost crab Persephona mediterranea Menippe adina Uca minax Ocypode quadrata Family Leucosiidae Family Menippidae Family Ocypodidae Family Ocypodidae Mudflat fiddler crab Spined fiddler crab Longwrist hermit Flatclaw hermit Uca rapax Uca spinicarpa Pagurus longicarpus Pagurus pollicaris Family Ocypodidae Family Ocypodidae Family Paguridae Family Paguridae Dimpled hermit Brown banded hermit Flatback mud crab Estuarine mud crab Pagurus impressus Pagurus annulipes Eurypanopeus depressus Rithropanopeus harrisii Family Paguridae Family Paguridae Family Panopeidae Family Panopeidae Page 2 Smooth mud crab Gulf grassflat crab Oystershell mud crab Saltmarsh mud crab Hexapanopeus angustifrons Dyspanopeus texanus Panopeus simpsoni Panopeus obesus Family Panopeidae Family Panopeidae Family Panopeidae Family Panopeidae Tube pea crab Longnose spider crab Portly spider crab Spotted porcelain crab Pinnixa chaetopterana Libinia dubia Libinia emarginata Porcellana sayana Family Pinnotheridae Family Pisidae Family Pisidae Family Porcellanidae Green porcelain crab Eastern tube crab Sargassum swimming crab Iridescent swimming crab Petrolisthes armatus Polyonyx gibbesi Portunus sayi Portunus gibbesii Family Porcellanidae Family Porcellanidae Family Portunidae Family Portunidae Florida lady crab Blue crab Speckled swimming crab Lesser blue crab Ovalipes floridanus Callinectes sapidus Arenaeus cribrarius Callinectes similis Family Portunidae Family Portunidae Family Portunidae Family Portunidae Blotched swimming crab Squareback marsh crab Gulf squareback crab Portunus spinimanus Armases cinereum Speocarcinus lobatus Family Portunidae Family Sesarmidae Family Xanthidae Page 3 Page 4 Page 5 Arrow Crabs - Inachidae Crabs in the Inachidae family belong to a group of crabs known as arrow (or spider) crabs. Their bodies are either round or triangular shaped, usually narrowing at the anterior end. They all have an extend rostrum anteriorly that may be short or extremely long and narrow, and either simple or forked. Their legs are narrow and long, resembling that of a spider. Their heads lack orbits for their eyes to lie into. Page 6 False arrow crab Metoporhaphis calcarata Family Inachidae - Spider crabs Carapace triangular, longer than wide, narrower in the front, knobby, knobs surmounted by a tubercle; long thin simple rostrum (extended snout), as long or Distinguishing longer than carapace, pointed; color brown to gray; eyes protrude sideways, no Characteristics orbits; claw appendages shorter than other legs; legs long and slender; long spine extending dorsally at 1st joint in legs with smaller spines ventrally. The yellowline arrow crab has a smooth carapace with yellow lines, no Similar Species prominent spines at joints on legs. Gulf, possibly high salinity bays; found around hydroids and other fouling Habitat organisms on hard substrates Maximum Size 2.4 cm (1 in) carapace length, 1 cm (<1/2 in) carapace width Page 7 Box Crabs - Calappidae and Hepatidae Some crabs of the Calappidae family have the ability to hide their legs and claws close to their shell, appearing box-like and inert, thus the name "box crabs". They are also known as "shame-faced" crabs for the way they hold their broad flat claws over the anterior region of their shell, as if hiding their face. Their claws are highly ornamental and are fringed with tiny hairs. It is believed that the hairs filter sand and other particles from water that is siphon into the body and across the gills to extract oxygen. This is useful when the crab is buried in the sediment. One claw has a specialized enlarged tooth that is used to "peel" open gastropod shells, similar to using a can opener. The family Calappidae has recently undergone revision and its genera were split into four different families. Of those families, only Calappidae and Hepatidae are present in the Gulf of Mexico. Page 8 Calico box crab Hepatus epheliticus Family Hepatidae - Box crabs Carapace oval, wider than long, narrowing at the posterior end; color light tan background with large reddish brown spots on carapace and legs, pinkish to Distinguishing white underneath; lateral margins with small blunt spines; claws broad, flat with Characteristics 3-4 teeth on crest; one claw with enlarged tooth on movable finger fitting into cup-like depression on immovable finger; claws mostly white, inside is smooth, outside is rugged; claws are held close to anterior carapace. Very similar to the flecked box crab. The pattern on the carapace easily Similar Species distinguishes the two. Calico box crab has large spots. Flecked box crab has transverse lines or very small spots. Habitat Gulf, prefers sand or muddy bottoms Maximum Size 8 cm (3 1/5 in) carapace width Page 9 Flecked box crab Hepatus pudibundus Family Hepatidae - Box crabs Carapace oval, wider than long, narrowing at the posterior end; color brownish with darker transverse broken rows that bend posteriorly at the lateral ends, alternately may be covered with small darker spots or a combination of Distinguishing transverse lines and spots; front at edge of carapace between orbits thick and Characteristics slightly bi-lobed; lateral margins with small blunt spines; claws broad, flat with 3-4 teeth on crest of claw; one claw with enlarged tooth on movable finger fitting into cup-like depression on immovable finger; claws mostly white, inside is smooth, outside is rugged; claws are held close to anterior carapace. Very similar to the calico box crab. The pattern on the carapace easily Similar Species distinguishes the two. Calico box crab has large spots. Flecked box crab has transverse lines or very small spots. Habitat Gulf Maximum Size 7.5 cm (3 in) carapace width Page 10 Yellow box crab Calappa sulcata Family Calappidae - Box crabs Carapace oval, wider than long, curved anteriorly, nearly flat posteriorly; color varies from pink to dark brown; lateral margins with spines, posterior one being Distinguishing the largest; claws broad, flat, distinct hump on anterior end before movable Characteristics finger; several teeth on crest of claw; outer surface with 2 rows of low tubercles (bumps), one claw with enlarged tooth on movable finger fitting into cup-like depression on immovable finger; claws are held close to anterior carapace. Looks similar to the flame box crab, but the flame box crab has irregular Similar Species markings or lines on its carapace. Habitat Gulf Maximum Size 14.5 cm (5 3/4) carapace width Other Common Names shamefaced crab Page 11 Fiddler Crabs and Ghost Crabs - Ocypodidae Ocypodidae is a family of mostly semi-terrestrial crabs that live in burrows in soft sand or mud within the intertidal stretches of bays and beaches. When the tide goes out, the crabs will come out of their burrows in search for food. While most crabs in this family live intertidally, some live a more aquatic life while others live supratidally in a more terrestrial setting. All must venture back to the water for breeding and normal larval development. Fiddler crabs are most easily distinguished by the oversized claw of the male. The male uses the enlarged claw for combat and communication. The smaller claw is used for feeding. The motion of the small claw being raised and lowered from the mouth gives the appearance of strumming the larger claw, thus the name fiddler crabs. Once the fiddler is through sifting through a claw full of sand for food, the sand is deposited in the form of a little ball. These balls are typically found outside the burrows of fiddler crabs. When male fiddler waves its larger claw in the air and taps it on the ground, he is displaying a courtship ritual in an effort attract a female. Ghost crabs have an enlarged claw also, but not quite the extent of the male fiddler. They are called ghost crabs because they are blend into their background and can easily disappear by running in zigzag lines with speeds up to 10 mph. Their stocked black eyes stand erect giving the ghost crabs 360° vision. Their vision is so acute they can spot and grab insects in mid-air. However, they cannot see directly above themselves which make them easy prey for birds. Ghost crabs are nocturnal, being more active at night than during the day. They are mostly found on beaches. Their burrow holes are about the size of a golf ball. Adult males rearrange the sand that is excavated from its burrow into a pile beside the hole. Adult females and juveniles just scatter the sand outside the holes. These tell-tale signs plus crab tracks around the holes indicate the home of a ghost crab. Page 12 Atlantic ghost crab Ocypode quadrata Family Ocypodidae - Fiddler and ghost crabs Carapace rectangle in shape; slightly longer than wide; color grayish white to