Excirolana chiltoni

(Richardson, 1905)

sand piranha

Excirolana chiltoni is a small intertidal isopod, commonly called 'sand piranha,' inhabiting sandy beaches of the Pacific Rim from Japan and Korea to Colombia. reach approximately 8 mm in length and form dense exceeding 1,000 individuals. The exhibits with direct development, a 2-year lifespan, and pronounced spatial segregation during breeding.

Excirolana chiltoni by (c) Lee Cain, some rights reserved (CC BY), uploaded by Lee Cain. Used under a CC-BY license.Excirolana chiltoni by University of California San Diego. Used under a CC BY-SA 3.0 license.The Biological bulletin (20192547319) by Internet Archive Book Images. Used under a No restrictions license.

Pronunciation

How to pronounce Excirolana chiltoni: /ɛk.si.roʊˈlæ.nə ˈtʃɪl.toʊ.naɪ/

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Habitat

Intertidal zone of sandy beaches (arenicolous), specifically the beach slope. Distribution within this zone is controlled by sediment suction (soil moisture tension). In high tidal range beaches, individuals move seaward as tide level drops.

Distribution

Pacific coasts: western Pacific from Japan and Korea to South China; eastern Pacific from Pacific Northwest (USA/Canada) to Chocó, Colombia. Temperate Northern Pacific region.

Seasonality

Most active during high tides. Breeding season extends from early April to late September in northern Japan . Growth rate is high in warm season and low in winter.

Diet

Scavenger/ feeding on proteinaceous materials, primarily decaying carcasses of dead aquatic animals washed ashore.

Life Cycle

Approximately 2-year lifespan. Cohort analyses indicate two or three age groups present in . : large -filled develop in paired uteri, progressing through five intrauterine stages. Birth produces manca stage, morphologically similar to but lacking the eighth pair of thoracic legs. Oostegites are reduced and form a genital rather than a functional pouch.

Behavior

Forms swarms of more than 1,000 individuals. Exhibits tidal : in high tidal range beaches, disperses seaward as tide level drops. During breeding season, shows spatial segregation with ovigerous females on the high shore and juveniles positioned closest to the sea.

Ecological Role

Representative small benthic isopod of sandy beach intertidal zones; scavenger contributing to decomposition of marine carrion.

Human Relevance

Occasionally bites and chews on skin of beachgoers and other animals, earning the 'sand piranha.'

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Sources and further reading