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Soil Invertebrates
Protura
• 0.5 – 1.5 mm
• ca. 500 species worldwide
• no eyes or antenna
• feed on organic matter and fungal spores
• inhabit moist soils and humus
• temperate deciduous forests
Diplura
• ca. 5 mm
• ca. 800 species worldwide
• no eyes
• inhabit moist soils, leaf litter, humus
• most are predators; also feed on organic
matter
• common in grassy and wooded habitats
Collembola (springtails)
• < 6 mm
• ca. 6,000 species worldwide
• > 300 million individuals/acre have been found in grasslands
• inhabit soils, leaf litter, fungi, decaying organic matter
• feed on decaying vegetations and fungi; a few species are herbivores
and predators
• common in grassy and wooded habitats
Bristletails and Jumping Bristletails
• 7 – 15 mm
• ca. 300 species worldwide
• inhabit leaf litter and decaying organic matter
• some species are common in buildings and feed on
starches in books, wallpaper, clothing, and paper
(silverfish)
• feed on decaying organic matter, fungi, algae, some
plant material
• live in grassy and wooded habitats
• jumping bristletails are very common in shrubsteppe
Isopods (Sowbugs and Pillbugs)
• 1 – 2 cm
• crustaceans (related to shrimp and crabs)
• pillbugs roll up into a ball when disturbed
• inhabit leaf litter and decaying organic
matter
• feed on decaying organic matter and
fungi; some feed on plant material
• breathe through gills
• carry 7-200 eggs in a brood pouch
Centipedes
• ca. 2,500 species worldwide
• 1 pair of legs per body segment (15 – 177 pairs, depending on species)
• first pair of legs modified into venemous fangs
• found in or on soil surface in moist habitats, under bark, stones, and logs
• predators (on insects, spiders, other small animals)
Millipedes
• ca. 2.5 – 10.0 cm
• ca. 80,000 species worldwide
• 2 pairs of legs on most segments (30 – 375 pairs of legs, depending on
species)
• found in or on soil surface in moist habitats, under bark, stones, and logs
• most species feed on decaying organic matter; a few species are predators
and herbivores
Earwigs
• ca. 1.5 – 2.5 cm
• ca. 1,800 species worldwide
• most have a pincer used for grooming, defense, and courtship
• found in or on soil surface in moist habitats, under bark, stones, and logs
• most species are scavengers or herbivores, feeding on a variety of plant
and animal matter; a few species are predators
Beetle larvae
White Grubs
• larvae of weevils, scarab beetles, blister beetles
• occur in grassy fields, crop fields, and rotten logs
• feed mainly on plant roots
•blister beetles are predators on grasshopper egg pods
Wireworms
• larvae of click beetles
• occur in grasses and crops
• feed on plant roots
Beetle larvae
Predaceous Forms
• larvae of ground beetles
• live in burrows in the soil, under leaf litter, logs
• occur in grassy fields, crop fields
• generalist predators on other invertebrates; some
species feed on snails and slugs
Mealworms
• larvae of darkling beetles
• occur in grasses, stored
grains, forests
• feed on live and dead
plant material
Fly larvae
(maggots)
• larvae are legless and often have indistinct heads
• occur in moist habitats, leaf litter, organic matter, decaying carcasses
• some feed on decaying organic matter (e.g. cranefly, moth flies, some
midges, muscid fly, blow fly, flesh fly)
• some feed on plants (e.g., cranefly)
• some feed on fungi (e.g., fungus gnats)
• some are predators and parasites (e.g., robber fly, dance fly, blow fly,
flesh fly, tachinid fly)
Moth larvae
(cutworms, armyworms, webworms)
• larvae have well-developed head capsules with chewing mouthparts
• larvae have 3 pairs of legs on the thorax and 2-5 pairs of prolegs
• common in grasses and cropland
• herbivores on plant roots and shoots
• can occur in very high numbers (e.g., sod webworms in grasslands)
• can be significant crop pests
Ant
• ca. 9,500 described species
• widely distributed in a variety of
habitats
• build nests in the ground or wood
• occur in very high numbers in colonies (e.g., 5,300 ants/m2 in a tropical
lowland forest in Brasil)
• have castes (e.g., workers, queen, soldiers)
• some species are seed-feeders (e.g., harvester ants)
• some species are strict predators (e.g., army ants, fire ants)
• some species omnivore, feeding on plants and animals
• most species are opportunistic foragers – feeding on a variety of live and
dead plant material
• “ecological engineers” – alter soils and environments
Pseudoscorpions
• ca. 2 – 8 mm
• ca. 200 species in North America
• large pincer-like claws; no stinger
• most species have a venom gland
• found in leaf litter and under bark and stones
• predators on small invertebrates (e.g., moth larvae, beetle larvae, ants,
mites)
• some live under the wings of beetles and feed on mites
Mites
• usually < 1 mm (up to 10 mm)
• ca. 45,000 described species
• extremely abundant in some habitats (e.g., up to 1 million per m2 of
coniferous forest litter)
• found in most terrestrial and aquatic habitats
• abundant in leaf litter and decaying organic matter
• feed on plants, organic matter, fungi, bacteria, protozoa, and animals
• influence decomposition by shredding and feeding on organic matter,
and fungi.
• some are major crop pests
Spiders
• ca. 2,500 species in North America
• found in all terrestrial habitats
• most have 8 eyes
• have poison glands
• some species spin webs
• eggs often laid in silken sacs
• predators on many invertebrates
Harvestmen
(daddy longlegs)
• ca. 5,000 described species worldwide
• have at most 2 eyes
• have no poison glands or fangs
• do not produce silk
• prefer moist habitats; found in forests, caves, grasslands
• feed on other invertebrates, plant material, decaying organic matter, fungi
Earthworms
• over 7,000 species worldwide
• no eyes
• occur in most temperate soils and many tropical soils
• can have 50 – 300 earthworms/m2 of crop soil
• prefer soils with abundant organic matter
• feed on organic matter and plant materials in soil; obtain nutrients from
bacteria and fungi in organic matter
• take soil in and deposit undigested food as “worm castes”
• can produce tons of casts per acre each year
• facilitate nutrient cycling, nutrient mineralization, and decomposition
• can turnover the top 15 cm of soil in 10 – 20 years
Nematodes
• typically < 1 mm
• about 20,000 described species
• can be very abundant (millions/m2)
• many trophic forms
•fungal feeders
•bacteria feeders
•predators on other nematodes and protozoa
•omnivores (feed on a variety of organisms)
• herbivores on plant roots
• animal parasites
• recycle nutrients by feeding on soil microbes and decomposing organic
matter