DOD Bestiary: Trilobite

Common Name: Trilobite (Shell-bug)
Pronounced: (Try-low-bite)
Classification: Trilobita / various sp.
SGOC Rank: Mesofauna / Fauna / Megafauna

Length: ½ inch – 12 feet
Height: ¼ inch – 2 feet (ground level)
Weight: ¼ oz. – 540 lbs.
Diet: Carnivore / Herbivore / Omnivore
Social Structure: Solitary, Swarm (20-1000+ members)
Home Planet: Earth
Distribution: Saltwater / brackish water worldwide
IUCN Status: Least Concern

Description:

Trilobites are some of the most successful animals of all time. These marine arthropods first emerged during the early Cambrian period and thrived worldwide until their sudden surface-world demise at the end of the Paleozoic; innumerable species of trilobite have survived in the planet’s various World Below caverns, and in our post-Cycle world they have returned with a vengeance.

Trilobites come in many different shapes and sizes, but all share a few basic characteristics. They all (save for a few soft-bodied species) have segmented exoskeletons that allow them to roll up in a ball for defense; this shell is molted periodically as the animal grows. Many species have simplistic shells while others are more ornate, sometimes forming elaborate horns and spikes for self-defense and digging. Trilobite eyes were advanced for their time, being compound structures with crystals of calcite forming the lenses; some of today’s deep-sea species are blind and instead navigate with their flickering antennae. Trilobites reproduce sexually and lay clusters of soft eggs, just like horseshoe crabs, and some species even venture onto beaches to mate and deposit their eggs in the wet sand.

Trilobites cover virtually every possible niche in the oceans. There are herbivores, predators, scavengers, planktivores, and even parasites among their numbers. Some rake the sand for soft-bodied prey with bizarre fork-like horns, others graze on algae-caked rocks like little vacuum cleaners, and others still flutter waves of seawater from their legs to expose buried carrion and microbial mats. Many species of trilobite, in particular the Dudley bug of the UK and the pachavee of the southeastern USA, are eaten as exotic seafood.

Not all trilobites are small and inoffensive, however. The group has dabbled in predatory niches in the past and has since refined its entries into truly frightening predators. The largest of these is the swamp trilobite (Flagellamonstrum paralyticus, “Paralyzing Monstrous-whip”), an amphibious twelve-foot predator with whip-like antennae that can paralyze even large animals with a potent neurotoxin; although native to the swamps of South America, this species’ eggs are resistant to saltwater and thus swamp trilobites can be found in humid coastal waters worldwide, including the Fire Swamp. An equally feared cousin of the swamp trilobite is Africa’s smaller and more social fire trilobite (Flagellamonstrum aceticus, “Monstrous-whip-of-acetic-acid”), a five-foot species whose whip-like antenna lash a caustic cocktail of acetic and caprylic acid, scorching flesh and blinding the victim before the arthropods emerge to rend it with their mulching jaws.