Hyperiidea

H. Milne Edwards, 1830

hyperiid amphipods

Family Guides

Hyperiidea is a suborder of exclusively marine amphipod crustaceans characterized by large and a planktonic lifestyle. Unlike other amphipod suborders, they do not occur in freshwater. The group comprises approximately 284 across 20-23 . Most species are associated with gelatinous zooplankton as or of salps and jellyfish, though some members such as Themisto gaudichaudii are free-swimming predators of copepods and other small planktonic animals.

Hyperiidae by (c) Георгий Виноградов (Georgy Vinogradov), some rights reserved (CC BY), uploaded by Георгий Виноградов (Georgy Vinogradov). Used under a CC-BY license.

Hyperiidae by (c) alicia penney, some rights reserved (CC BY), uploaded by alicia penney. Used under a CC-BY license.

Phronima by (c) Steve Kerr, some rights reserved (CC BY), uploaded by Steve Kerr. Used under a CC-BY license.

Pronunciation

How to pronounce Hyperiidea: /ˌhaɪpəˈrɪdiːə/

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Images

Habitat

Exclusively marine; planktonic. occupy pelagic zones from surface waters to depths exceeding 1500 m. Some species show distinct vertical patterns, moving from surface waters (0-50 m) as juveniles to daytime depths of 100-300 m as . Temperature preferences vary: some species are restricted to cold Arctic waters (<8°C), while others prefer warm waters (>25°C) of relatively high salinity (>35).

Distribution

in marine waters worldwide. Documented from the Southern Ocean (69 ), Greenland Sea, Alaskan coastal waters (56°N to 70°N), Gulf of California, western Mexico, southern Gulf of Mexico, northern Queensland waters, and the Mediterranean Sea. Species distributions often correlate with water mass characteristics, with some serving as indicators for Atlantic, Arctic, or warm-temperate waters.

Seasonality

Activity patterns vary by and region. In northern Queensland waters, hyperiids were generally most abundant during October-December and April-July. Some species reproduce year-round with seasonal peaks, while others show more restricted breeding periods.

Diet

Most are or of gelatinous zooplankton, particularly salps and medusae. Free-swimming predatory species such as Themisto gaudichaudii and Parathemisto species feed primarily on calanoid copepods (approximately 50% of diet) and compound-eyed crustaceans including euphausiids and other amphipods (approximately 30%). has been observed, with higher in some species.

Host Associations

Salpida - /Most hyperiid are or of salps
Medusae - / Brachyscelidae preferentially associated with medusae
Copepoda - Free-swimming such as Themisto and Parathemisto feed on calanoid copepods
Euphausiacea - Prey for predatory hyperiids including Parathemisto

Life Cycle

Development includes direct development without larval stages; females carry and young in a pouch. duration varies: some such as Parathemisto libellula complete a 1-year life cycle with broods released in early May, while others such as P. pacifica reproduce year-round with times of 6-12 weeks depending on season. Juveniles typically occur in surface waters (0-50 m) and undergo vertical to deeper daytime depths as they grow.

Behavior

Vertical is a prominent : juveniles inhabit surface waters and migrate to deeper daytime depths (100-300 m) as they mature. Some show diel vertical migration patterns. Metabolic adaptations to salinity changes may maintain constant metabolic rates during vertical movement. occurs in some species.

Ecological Role

Significant in pelagic , consuming copepods, euphausiids, and other crustaceans. Serve as for water mass identification: Themisto compressa indicates southern Atlantic water, while T. abyssorum and T. libellula are associated with Arctic and -subarctic waters. Facilitate year-round pressure on zooplankton through seasonal partitioning among congeneric .