Parhyale hawaiensis is an amphipod crustacean

Crustacean

Crustaceans form a very large group of arthropods, usually treated as a subphylum, which includes such familiar animals as crabs, lobsters, crayfish, shrimp, krill and barnacles. The 50,000 described species range in size from Stygotantulus stocki at , to the Japanese spider crab with a leg span...

 species that is used in developmental

Developmental biology

Developmental biology is the study of the process by which organisms grow and develop. Modern developmental biology studies the genetic control of cell growth, differentiation and "morphogenesis", which is the process that gives rise to tissues, organs and anatomy.- Related fields of study...

 and genetic

Genetics

Genetics , a discipline of biology, is the science of genes, heredity, and variation in living organisms....

 analyses.

Habitat

P. hawaiensis is a detritovore that has a circumtropical, worldwide, intertidal, and shallow-water marine distribution, and it may occur as a species complex

Species complex

A species complex is a group of closely related species, where the exact demarcation between species is often unclear or cryptic owing to their recent and usually still incomplete reproductive isolation. Ring species, superspecies and cryptic species complex are example of species complex...

. It has been reported to occur in large populations (more than 3000 per square metre) on decaying mangrove

Mangrove

Mangroves are various kinds of trees up to medium height and shrubs that grow in saline coastal sediment habitats in the tropics and subtropics – mainly between latitudes N and S...

 leaf material in environments subjected to rapid changes in salinity

Salinity

Salinity is the saltiness or dissolved salt content of a body of water. It is a general term used to describe the levels of different salts such as sodium chloride, magnesium and calcium sulfates, and bicarbonates...

. The ability to tolerate rapid temperature and osmotic changes allows this species to thrive under typical laboratory conditions.

Life cycle

Females produce embryo

Embryo

An embryo is a multicellular diploid eukaryote in its earliest stage of development, from the time of first cell division until birth, hatching, or germination...

s every 2 weeks once they reach sexual maturity

Sexual maturity

Sexual maturity is the age or stage when an organism can reproduce. It is sometimes considered synonymous with adulthood, though the two are distinct...

. Embryogenesis

Embryogenesis

Embryogenesis is the process by which the embryo is formed and develops, until it develops into a fetus.Embryogenesis starts with the fertilization of the ovum by sperm. The fertilized ovum is referred to as a zygote...

 is relatively short, lasting about 10 days at 26 °C (78.8 °F). Females normally brood the embryos in a ventral brood pouch. Close examination of the embryonic development of P. hawaiensis has produced the most detailed staging system for any crustacean. Complete embryogenesis has been divided into 30 discrete stages, which are readily identifiable in living animals or by means of common molecular markers in fixed specimens. Hatchlings possess a complete complement of segments and appendages which are morphologically

Morphology (biology)

In biology, morphology is a branch of bioscience dealing with the study of the form and structure of organisms and their specific structural features....

 similar to those of adult animals.

Genetic research

P. hawaiensis is used in genetic research because eggs and embryos are easily manipulated. Embryos can be rapidly and easily removed from the brood pouch and maintained in seawater. Eggs can be collected and hatched individually, and the mature animals can subsequently be used in pairwise sister-brother or mother-son matings to generate inbred lines.

Fertilized eggs are sufficiently large to perform microinjections and blastomere

Blastomere

A blastomere is a type of cell produced by division of the egg after fertilization.- References :* "Blastomere." Stedman's Medical Dictionary, 27th ed. . ISBN 0-683-40007-X...

 isolations with relative ease. Developing P. hawaiensis embryos are clear, allowing for both detailed microscopic analyses in situ

In situ

In situ is a Latin phrase which translated literally as 'In position'. It is used in many different contexts.-Aerospace:In the aerospace industry, equipment on board aircraft must be tested in situ, or in place, to confirm everything functions properly as a system. Individually, each piece may...

and the use of fluorescently tagged tracer molecules in live embryos. Early cleavage is holoblastic (total), allowing the fates of individual early cells to be explored through experimental manipulation.