Other soil animals
Other soil animals
Here are some more animals, covered here in a broader fashion, due to time, motivation and the sheer overwhelming wealth and profusion of Collembola and mites that need to be photographed. I'll keep expanding and updating with the hope of eventually giving more animals their own page. They deserve it. Until then, I hope they will forgive the brevity. They're all still amazing, each one worthwhile and special in their tiny little ways.
Nematodes, also known as roundworms, are everywhere. A famous quote by Nathan Cobb suggests that if all the matter in the world was swept away, leaving only nematodes, then ghostly, nematode-filled shapes would remain of every single thing. Oceans, humans, trees... That's how amazing and numerous they are. And I must agree, they're great little things.
Nearly half of all nematodes are parasitic, many capable of causing diseases and problems in plants and animals, including humans.
Some nematodes are a common sight, travelling relatively harmlessly on Collembola and other micro-arthropods, though the unwilling transportation can certainly exhibit some discomfort.
Some of the larger non-parasitic nematodes are the free-living soil nematodes, and the easiest to photograph. These ones below are around 2mm, end to end. Over countless millennia they have become able to take advantage of practically any food source. They can be predatory, or feed on fungi, live or dead animals, detritus or bacteria.
Nematodes basically consist of an outer tube of cuticle, containing two other smaller tubes, the pharynx/ intestine and the reproductive system. Below, you can see the pharynx leading from the head part leading to the start of the intestine. The majority of the body is dominated by the reproductive system, seen here by the defined area of darker yellow. This is in stark contrast to the Enchytraeids, whose gut and digestive contents can be tracked from head to tail.
They also have an interesting muscle structure which means, apart from the head, which has more mobility, the body can only flex dorsally and ventrally, which looks a little like mindless thrashing in the soil.
The enchytraeids are often known as pot worms as they'll often show up in the compost when gardeners are transplanting plants to bigger pots. Famous enchytraeids include the ice worms that live on glaciers and die if exposed to temperatures much above freezing.
Another very commonly seen larva is that of the Mycetophilidae. They're normally found in the soil under bark and fallen logs, but unlike their distant cousins, the Forcipomyiidae, many larvae of Mycetophilidae, or fungus gnats, live in a semi-manufactured environment, surrounding themselves in a sticky webbing that they travel backwards and forward in. They're slime travellers.
They usually eat fungi, fungal hyphae and spores, although some species can be slightly predatory.
Mycetophilidae, like the ones here, have specialised mouthparts, enabling them to spin a sticky web that controls the humidity of their environment as well as for safety.
Ostracods, also sometimes known as seed shrimps, are usually aquatic. However, certain places have them also as a terrestrial crustacean, the superfamily Terrestricytheroidea. Originally discovered in South Africa, they are now also known from New Zealand, UK and Australia. The photographs here are of a Mesocypris species from New Zealand, probably M. audax. This guy is around 0.5mm big though this species can get up to around 1mm. They coast around in the film of water covering the underside of wet logs as well as leaf litter and soils of native forests.
To get around the problem of still being an aquatic, though adapted animal, they are able to carry water in and around their shells, using specialised hairs to trap the liquid which spreads around them as they travel. If their limited water supply isn't periodically replenished, they perish.
Research from New Zealand in the 1980s shows that they are only able to thrive within specific and narrow moisture and temperature parameters, autumn being their most common period.
Mite harvestmen are little known cryptic arachnids, although almost worldwide in distribution, except for the continent of Antarctica. They're otherwise known as Sironids or Cyphophthalmi. They are a suborder of Opiliones, but usually much smaller than their long-legged cousins- between 1.5 and 5mm big. As the common name suggests, they bear more than a passing resemblance to mites, including having a tiny size. They can be often mistaken for Opilioacarids, although unrelated. Interestingly, like all Opiliones, they are more closely related to scorpions than spiders. They are extremely dispersal-limited, meaning that each species, with one exception, is limited to a very small area. Not surprisingly, perhaps, their movements are sloth-like slow.
They live in the leaf litter of undisturbed, temperate, sub-tropical and tropical forests across thew world, though only needing very small preserved areas in which to survive.
The family Pettalidae, of which the orangey-brown Austropurcellia species from North Queensland below belongs to, has a wonderfully textbook Gondwanan range, only being found in parts of Australia, New Zealand, Chili, South Africa and Sri Lanka.
The two yellowish bulbs seen on either side of the Austropurcellia are not eyes, but in fact elevated cones called ozophores, at the top of which are defensive scent glands, called ozopores. The cones are unique to Cyphophthalmi. Most species have rudimentary eyes, situated at the base of the ozophores.
Planarians and Nemerteans
Planarians and Nemerteans
Planarians are very unusual. They are mainly aquatic, alongside a large group of vertebrate-parasitising flatworms known as tapeworms. But some species have become fully terrestrial, free-living in damp soils, leaf litter and under logs. They can be as small as 3mm, as large as 15-30mm. Some have the ability to entirely regenerate themselves to such an extent that, like the Sorcerer's Apprentice, only a small section of the body is needed as a template to begin regrowth. Not only that, some can be bisected lengthways or chopped in two midway and turn into two fully functioning animals. Losing a head isn't a problem. They just grow another one.
The pharynx, or eversible feeding tube is situated on the body's underside, halfway down. It also functions as an anus. Because of this they have to fully digest every meal and excrete before eating again.
Some terrestrial species have just two ocelli or eyes, like the snake-headed flatworm, R. sylvestris below, a native flatworm from the UK. Others can have an array of hundreds of light sensitive pigmented dots along their flanks.
Flatworms get their name for when they are at rest, or disturbed. They dorsally flatten, thicken and contract their length as with the K. andersoni above. The animal below is the same one, stretched back to its full length, moving slowing across the substrate on its mucus slime.
They often have a taste for worms, like the infamous New Zealand flatworm, wreaking its tiny havoc across the gardens of the UK. They can also eat slugs, snails woodlice and insects.
Certain species of the Bipalium or hammerhead flatworms use the deadly neurotoxin, tetrodotoxin or TTX to immobilise their prey. This makes flatworms the only fully terrestrial animal so far discovered to use it. There is no antidote. Famously, it is the same compound present in Fugu, the Japanese puffer fish delicacy, which kills adventurous Japanese diners every year.
Nemerteans are otherwise known as ribbon worms, proboscis worms or more ominously, smiling worms. They are usually aquatic and predatory and can be anything up to 30 metres long. However, there are a few southern hemisphere species that are relatively tiny and fully terrestrial, like these ones. And they are a little strange.
All nemerteans have an eversible proboscis, which is definitely one of the grosser things to watch with a magnifying glass. At rest, the proboscis lies in a cavity along almost the full length of the body. When attacking prey, the front end of the animal instantaneously everts an enormous white mass of venomous, sticky mouthparts, completely covering the possible food. It can be retracted almost as quickly.
All nemerteans travel on a trail of their own mucus, making them initially easy to confuse for a slug or a flat worm as I did once, getting the shock of my life when it everted all over a woodlouse.
They also share an ability with the flat worms to have a body that can thicken and shorten when disturbed or at rest, and telescope and become thinner when moving. They can also have hundreds of the light-sensitive simple pigment-cup eyes, like the flatworms.
As exotic species, they have been transported into the northern hemisphere by human activity. The UK has at least three species, probably from Australia originally. First observed around twenty years ago, they are rapidly expanding their south-west and southern range.
Also known as micro mollusks because it sounds more sciency.
Micro snails are found worldwide, mostly as aquatic species, though as you may have guessed, there are plenty of fully terrestrial species. This includes the world's smallest snail, which, if you're a micro snail, was always probably going to be on the cards. So far, the tiniest title goes to a 0.7mm snail, known as Acmella nana from Borneo.
Terrestrial micro snails don't just wander about outside. There are some species that are adapted to cave life like the Zospeum species below from Slovenia, feeding on the clay substrate. They are known as glass snails and are transparent and completely blind.