Amphipods

Pronunciation

How to pronounce Amphipoda: //æmˈfɪpoʊdə//

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Summary

Amphipods are diverse, largely aquatic crustaceans characterized by their laterally compressed bodies, absence of carapace, and a wide range of habitats. They play crucial roles as detritivores and grazers in aquatic ecosystems.

Physical Characteristics

Amphipods have a laterally compressed body divided into 13 segments: a fused head and thorax, and an abdomen. They bear two pairs of antennae, one pair of compound eyes, and possess uniramous appendages on the thorax. The abdomen has swimming legs and a telson.

Identification Tips

A clear view of the antennae is needed to identify freshwater amphipods beyond the order level.

Habitat

Amphipods occupy a wide range of aquatic environments, including fresh water, marine waters, and saline environments, as well as some terrestrial habitats like leaf litter.

Distribution

More than 9,900 species are described worldwide; about 1,900 species live in fresh water, with significant biodiversity noted in places like Lake Baikal and the Caspian Sea basin.

Diet

Predominantly detritivores or scavengers, some amphipods graze on algae or can be omnivores and predators of small insects and crustaceans.

Life Cycle

Amphipods do not have larval stages as their eggs hatch directly into juvenile forms. Growth includes five to six molts before reaching sexual maturity.

Reproduction

Males grasp females in a behavior called amplexus, lasting from two to over fifteen days, after which the female molts, allowing fertilization. Females possess a marsupium for holding fertilized eggs until they are ready to hatch.

Predators

Fish are primary predators of amphipods, influencing their population dynamics and community roles in aquatic ecosystems.

Ecosystem Role

Amphipods are vital components of aquatic ecosystems, serving as mesograzers and controlling the growth of algae; they are also important food sources for various aquatic animals.

Cultural Significance

Known to anglers as 'freshwater shrimp,' 'scuds,' or 'sideswimmers.'

Health Concerns

There are rare reports of amphipods biting humans, but their bites are not venomous and do not cause lasting damage.

Evolution

Amphipods are believed to have originated in the Lower Carboniferous, but the fossil record is sparse with only a few known species from the Cretaceous period.

Similar Taxa

• Isopoda
• Coepepoda

Misconceptions

Amphipods are sometimes mistakenly categorized as shrimp due to their appearance and common names; however, they are distinct from true shrimp in various anatomical and ecological aspects.

Tags

• crustaceans
• biodiversity
• aquatic ecosystems
• marine life
• freshwater biology