Pentidotea resecata (Stimpson 1857)

How to Distinguish from Similar Species: No other local isopod has a concave posterior margin to its pleotelson.

Depth Range: Intertidal to 18 m

As in all valviferan isopods, the uropods of this species form platelike folds over the ventral side of the abdomen. Pentidotea resecata has a flattened body with 7 free pereonites. The lateral margins of the cephalon do not have a deep incision. The eyes are lateral. The pleon has two free pleonites plus the pleotelson, which has a pair of lateral incisions showing where a third pleonite is partially fused to the pleotelson. The palp of the maxilliped has 5 articles. The posterior margin of the pleotelson is concave. A green pigment is deposited in the endocuticle while a red pigment appears in the exocuticle, often resulting in a brownish overall body coloration, especially when living on Macrocystis. Those living on eelgrass are more green. Males generally have a green stripe running down their back. Said to be up to 4 cm long; but the male below is 5 cm long.

Biology/Natural History: When placed on a substratum, the isopod will reorient itself along the long axis of its substratum and if placed otherwise, it immediately reorients itself. P. resecata prefers to feed on algae such as Macrocystis, Pelagophycus porra, Eisenia arborea, Pterygophora californica, and Egregia laevigata, or on eelgrass. These animals appear to be temperature and salinity sensitive. A temperature of 15 degress Celsius is an optimum temperature for P. resecata. If temperatures reach between 29 and 31 degrees Celsius, the animal will die. If the isopod is placed in fresh water it survives a little over an hour in comparison with 33 hours in 125% seawater. Development of these isopods is a bit unclear, but studies show that the general body form changes little during growth. Features such as segment number and setae number vary directly with size, each molt providing further change. The species blends in with the kelp or eelgrass that it is on, and can also swim well using its pleopods.

Geographical Range: Pentidotea resecata generally appear from Alaska to the tip of Baja California and Mazatlan. They prefer to be among eelgrass or kelps.

Pentidotea resecata, the eelgrass isopod, is a species of isopod in the family Idoteidae. It is found in North America.

Pentidotea resecata là một loài chân đều trong họ Idoteidae. Loài này được Stimpson miêu tả khoa học năm 1857.

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