Octochaetus multiporus
Octochaetus multiporus is a deep-burrowing earthworm native to New Zealand. It grows up to 30 cm in length and emits bioluminescent fluid when disturbed.
Scientific classification
Kingdom
Animalia
Phylum
Annelida
Class
Clitellata
Subclass:
Oligochaeta
Order
Haplotaxida
Family
Megascolecidae
Genus
Octochaetus
Species
multiporus
New Zealand has close to 200 native earthworm species, with new species still being identified. In spite of this richness in species, we don’t know much about their population densities, life cycles or their distribution. We do know that, when native forest or tussock grasslands are cleared for agricultural development, native earthworms (especially the topsoil species) disappear. However, one species of native earthworm, Octochaetus multiporus, appears not to be as dependent on native vegetation and in some circumstances can successfully survive in modified habitats. Because of its relative abundance, O. multiporus has received more research attention than many other native species.
New Zealand native earthworm O. multiporus
New Zealand has over 200 known species of earthworms. Most of these are natives and are found nowhere else in the world. Many of our native earthworms live in remote forest habitats so we don’t know much about them.
O. multiporus is a large deep-burrowing native earthworm. Its bioluminescence made it a traditional fishing bait and lure for Māori.
O. multiporus are anecic earthworms. They live in the subsoil to a depth of up to 3–5 metres. They are found throughout the southern half of the North Island, in the South Island east of the main divide and in Stewart Island. O. multiporus need moist soil conditions to survive. Their populations are greater in soils that slope away from the Sun and are absent at adjacent sites where the land slopes toward the Sun (soils that are likely to dry out in the summer). Because they live so far down in the soil, they are not as affected by habitat change as earthworms that live closer to the soil surface. O. multiporus make extensive burrow systems. They use mucus (coelomic fluid) to form a cement-like substance to line their burrows. This mucus not only helps to keep the burrow walls from collapsing, but it may also be part of the species’ defence system because it is toxic to soil bacteria.
Octochaetus multiporus
O. multiporus is native to New Zealand. It is a large earthworm, growing up to 30 cm in length and 1 cm in diameter. It is pale in colour with a purple streak that runs along the top of its body. O. multiporus lives in the subsoil at depths of 3–5 metres. It makes extensive, permanent burrows. O. multiporus is bioluminescent. When disturbed, it squirts out a bright yellow-orange fluid that glows in the dark. Māori traditionally used O. multiporus as baits and fishing lures.
Scientific name: Octochaetus multiporus
Status: native
Soil niche: anecic
Length: up to 300 mm
Image: Ross Gray
Physical characteristics
To the average person, most earthworms may look alike, but O. multiporus has a few characteristics that set it apart. First of all, it is a large earthworm species. O. multiporus can grow up to 30 cm in length and have a width of 8–10 mm in diameter. They are pale in colour with a translucent body wall. A purple streak runs along the dorsal (top) midline of their bodies. Mature specimens have a darker pink clitellum (saddle). Overall, O. multiporus have weakly developed muscles, with the exception of the muscles near the head and tail. These muscles are used for burrowing and simply to help such large earthworms move. Their movements are quite sluggish when compared to earthworms that live higher up in the soil profile.
Bioluminescent fluid
Octochaetus multiporus squirts out coelomic fluid that glows in the dark. This bright orange-yellow light made O. multiporus desirable fishing bait to Māori.
O. multiporus is also unusual because it is bioluminescent. O. multiporus squirts out coelomic fluid from its mouth, anus and dorsal (underside) pores when it is disturbed. The fluid emits a bright orange-yellow light that glows in the dark. It has recently been discovered that the fluid glows in different colours depending on the age of the earthworm. Larger quantities of the luminescent liquid are produced if these earthworms are pierced. For this reason, Māori traditionally used O. multiporus as bait and lures when fishing. ‘Herehere tuna’ refers to a bunch of worms for catching eels.
Nature of science
All scientific knowledge is produced and valued within a wider society and culture. For example, agronomists and others in the scientific community value O. multiporus earthworms for their ability to improve soil structure, aeration and water-holding capacity in pastures. In addition, Māori communities value their usefulness in traditional methods of fishing.
Related content
Discover more about New Zealand's native and introduced earthworms.
Activity ideas
In Wormface – social networking for earthworms, students develop a profile for an earthworm species. To do this, they must research its scientific and common names, its physical characteristics and the role it plays in the soil ecosystem, they then record this information in a creative and novel manner.
In New Zealand soil creatures, students use Hub resources to learn about two unusual native New Zealand soil creatures. This cross-curricular activity combines science with reading, viewing, writing and presenting.
