Class Diplopoda

Millipede means a "thousand legs" until recently no diplopod was believed to have achieved this - the record was 750 in Illacme plenipes which is found in California. Until 2021 that is when a new species, Eumillipes persephone, was described. The beast was first discovered during exploratory mineral drilling in Western Australia. It was collected from 60m below ground. When a few juveniles were found in some of the drill holes, the researchers set a trap and collected five adults. Quite apart from the revelation that there is life at such depths, the adults had an unprecedented 1306 legs.

The class, to which millipedes belong, Diplopoda - is named after their characteristic feature - they have two legs per body segment. But it isn't all quite how it appears because each current segment reflects the fusion of two ancestral segments.

Unlike the centipedes, which they superficially resemble, millipedes are generally slow moving detritivores or omnivores and play an important role in many ecosystems by recycling of nutrients and energy from fallen leaves.

Found in every continent (except of course - you guessed it - Antarctica) they are represented by approximately 12,000 species with many more yet to be described. To put that in perspective, there are around 10,000 bird species known.

Despite moving slowly and having no obvious defenses, millipedes have several ways to avoid predation. In those species with heavy external armor they roll into a spiral, or a ball, with their more delicate legs folded inwards. This may be sufficient to deter some predators. Other millipedes are more militant and can expel fluids from pores known as ozopores.

The giant Fijian millipedes can produce secretions from these pores too. I once collected some Fijian tree frogs and made the mistake of putting a giant millipede with them as well. The next morning all the frogs were dead and the millipede had started eating them. Later, I left a giant millipede in a plastic cookie jar and was appalled to find that the plastic frosted from millipede excretions. After all this you'd think I'd know better than to sniff one. I wrangled a giant millipede for a TV film crew and injudiciously decided to sniff the animal. Bad mistake, the impact of the odor was so immediate and immense that I badly cricked my neck jerking my head away. Later I read that some millipedes produce hydrogen cyanide gas which is violently ejected after mixing two separate compounds in an "explosion chamber" - quite a deterrent - a schnozzz full of cyanide.

A few species are bioluminescent and experiments have shown that mammalian predators avoid the bioluminescent individuals. The bioluminescence stems from the exoskeleton but how it is produced is not yet known.

Interestingly, some millipedes fluoresce under ultraviolet light. I was fascinated when I first read about this and was able to find a Fijian millipede that does this. The photos aren't up to my usual standard but are included out of interest.

Millipedes today range in size from the tiny (2mm) to the giant (35cm) but today's biggest species doesn't approach the enormity of some of the extinct species. Some grew to over 2m and were the largest terrestrial invertebrate to ever exist (please understand there is an unwritten "as far as we know" after every statement - science moves quickly and what is true now may already be obsolete or even wrong tomorrow). These giants, belonging to the genus Arthropleura, were able to survive because of a lack of large terrestrial predators and a higher level of oxygen than is found today.

For more on millipedes check out Wikipedia.

Desmoxytes planata Dragon millipede

Desmoxytes planata Dragon millipede, introduced into Fiji and many other tropical countries from South East Asia

Fluorescent Fiji millipede

Orthoporus ornatus, Sonoran desert millipede

Procyliosoma delacyi New Zealand pill millipede

Riukia species

Trigoniulus corallinus, Fiji (introduced)

Unidentified millipede 1

Unidentified millipede, Rock View, Guyana

Unidentified millipede 2