Soil Invertebrates

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Soil Invertebrates
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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

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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

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Collembola (springtails)

• lt 6 mm
• ca. 6,000 species worldwide
• gt 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

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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

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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

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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)

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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

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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

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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

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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

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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)

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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

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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

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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

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Mites

• usually lt 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

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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

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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

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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

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Nematodes

• typically lt 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

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