metazoa5

"Never loose the opportunity of seeing anything beautiful,

for beauty is God's handwriting."

Ralph Waldo Emerson (1803-1882)

Poet and essayist

Yellow-banded millipede, Anadenobolus monilicornis. Creque Dam, north-western Saint Croix, United States Virgin Islands.

The arthropod sybphylum Miariapoda are an assemblage that comprise several closely related classes of arthropods with bodily frames divided into many, very similar, segments. The two best-known classes of this group are the diplopods (millipedes), with two pairs of legs per somatic segment, and the chilopods (centipedes), with one pair of legs per segment. As an additional distinction between them, all centipedes are fast and fierce predators of other arthropods, while millipedes are herbivores or saprophages, with but a few species secondarily adapted to occasionally feed on slow-moving prey.

Undulating Patterns

CLASS DIPLOPODA: MILLIPEDES

Together with scorpions, millipedes were perhaps the first arthropods to leave water and invade land, back in the Silurian period. They were part of terrestrial ecosystems even before insects had appeared on Earth. Generally, diplopods are herbivores or mycophages (they feed on fungi). Many can secrete toxic substances of repulsive flavor that keep predators at bay, and possess aposematic, "don't mess with me" color patterns in combinations of blacks, reds, and yellows that advertise their unpalatability (though some Antillean galliwasps - a group of anguid lizards - feed mainly on them).

Aside from toxins, and given the fact that for all their legs millipedes are very slow, many species exhibit a defense mechanism consisting in curling into a tight spiral. This protects the more vulnerable belly and also brings attackers into closer contact with the toxin-ejecting pores on their sides.

In spite of their name ("thousand feet") no species actually has that many legs. Indeed, some species (the "pill" millipedes), are very short, possessing rather few body segments and pairs of legs.

Subclass Helminthomorpha

The males of this group have the two pairs of legs in the seventh segment modified into organs that tranfer sperm to the females. They are a large and widespread taxon most abundant in the tropics.

Order Spirobolida

Spirobolids include moderate to very large species and some of these - particularly members of the family Rhinocricidae - are the most conspicuous millipedes of the West Indies, especially in the Greater Antilles. All species are detritivores and feed of dead plant matter and fungi. Many secrete foul-smelling and -tasting toxins from pores on their sides, which deter potential predators.

Puerto Rican giant millipede, Rhinocricus parcus. Toa Alta, north-eastern Puerto Rico.
It is almost as thick as a human thumb, and it and similar species defend themselves with noxious secretions from pores found on each segment.

The genus is a Greater Antillean endemic taxon and, interestingly, it is found only in Cuba (three or four species) and Puerto Rico (this one), skipping Hispaniola, between the other two islands.

Giant millipede, Rhinocricus suprenans. El Yunque de Baracoa, eastern Cuba.

This individual shows the defensive behavior of curling tightly upon being touched.

(Photograph courtesy of Dr. David Ortiz Martinez).

Hispaniolan giant millipede, Alcimobolus domingensis.
First photograph: near Santa Bárbara de Samaná, northeastern Dominican Republic.
Last two photographs: Santo Domingo, southern Dominican Republic, Hispaniola.

The diverse subspecies of the Puerto Rican tree millipede Anadenobolus arboreus can be strikingly different in color. Compare these individuals to the ones below.
This is the nominate subspecies, A. a. arboreus.

First photograph: Guana Island, British Virgin Islands.

Second photograph: Mount Sage, west-central Tortola, British Virgin Islands.

Anadenobolus arboreus josueotonieli. Guanica State Forest, south-western Puerto Rico.

Yet another subspecies: Anadenobolus arboreus leucosomus. Cambalache State Forest, northern Puerto Rico.

Intergrade between A. a. arboreus and A. a. leucosomus. Toa Alta, north-eastern Puerto Rico.

An undetermined subspecies of Anadenobolus arboreus. Guajataca, north-western Puerto Rico.

An undetermined subspecies of Anadenobolus arboreus. Guajataca State Forest, north-western Puerto Rico.

Yellow-banded millipede, Anadenobolus monilicornis. San Juan, north-eastern Puerto Rico.

Rhinocricid millipedes, possibly Anadenobolus excisus. Windsor, north-central Jamaica.

Millipede, Spirobollelus richmondi. Carite State Forest, east-central Puerto Rico.

Order Polydesmida

These millipedes are flattened, blind and secrete hydrogen cyanide in order to stay off attackers. Most species have 20 segments to their bodies.

Polydesmid millipede, Ricodesmus mauritii. Guilarte State Forest, west-central Puerto Rico.

Polydesmid millipedes, Dendrodesmus yuma. Cerro Diamante, central Dominican Republic, Hispaniola.

Polydesmid millipede, Cyrtaphe domingensis. Pico Diego de Ocampo Nature Reserve, north-central Dominican Republic, Hispaniola.

Subclass Helminthomorpha

These are the pill millipedes, so named after their shape when they roll unto a tight ball as a defense mechanism. They have between 11 and 13 segments in their bodies and are very short compared to other members of the class. They are often confused with wood lice (a group of terrestrial crustaceans) and indeed have very similar ecologies. However, they are not related.

Order Glomerida

This is the only order found in the Antillean islands. Like most millipedes they are often encountered in damp places under rocks and debris. Often rolling into a defensive posture as soon as they are uncovered they feed of dead organic matter.

Pill millipedes, Haplocyclodesmus sp. Negril, Jamaica