Isopods

Pronunciation

How to pronounce Isopoda: /ˌaɪsəˈpoʊdə/

These audio files are automatically generated. While they are not always 100% accurate, they are a good starting point.

Images

Summary

Isopoda is an order of crustaceans with a diverse array of species, adapted to both aquatic and terrestrial ecosystems. They play important ecological roles and exhibit varied feeding and reproductive strategies.

Physical Characteristics

Flattened dorsoventrally with a chitinous exoskeleton and segmented body. Generally grey, white, red, green, or brown in color. Size ranges widely from 0.3 mm to nearly 50 cm depending on the species.

Identification Tips

Look for rigid segmented bodies with two pairs of antennae, seven pairs of jointed limbs on the thorax, and five pairs of branching appendages on the abdomen. Notable terrestrial forms can roll into a ball.

Habitat

Isopods inhabit a wide range of environments including marine, freshwater, and terrestrial ecosystems. They can be found on the sea floor, in freshwater bodies, or crawling in moist terrestrial habitats.

Distribution

Over 10,000 species worldwide, with significant populations in marine (around 4,500 species), freshwater (about 500 species), and terrestrial environments (approximately 5,000 species).

Diet

Varied diet including detritivores, grazers, predators, parasites, and filter feeders. Terrestrial species typically feed on moss, bark, algae, fungi, and decaying material.

Life Cycle

Life cycle includes brooding eggs in a marsupium beneath the thorax. Eggs hatch into mancae, a post-larval stage. Moulting happens in two phases, unlike other crustaceans that do it in one stage.

Reproduction

Males and females are typically separate; some species are hermaphroditic. Males transfer sperm to females using modified pleopods, and females brood eggs in a chamber formed by oostegites under the thorax.

Predators

Isopods may face predation from various marine and terrestrial animals, including fish and larger invertebrates.

Ecosystem Role

Isopods play significant roles in ecosystems as decomposers, recycling nutrients, and aiding in the decomposition of plant materials.

Economic Impact

Some species have economic significance, particularly parasitic isopods that can impact commercial fisheries by damaging or killing host fish.

Evolution

Isopods first appeared during the Carboniferous period, about 300 million years ago. Initial fossil records show marine adaptations, with some groups later adapting to terrestrial life.

Similar Taxa

• Amphipoda
• Malacostraca

Misconceptions

Despite common names like pillbugs or sowbugs, not all isopods are harmful or pests; many are beneficial decomposers.

Tags

• Crustaceans
• Arthropods
• Isopods
• Ecology
• Biodiversity