Colossal Harvestman (Maiacaulos rex)
Although they are often mistaken for spiders, the order of arachnids called the harvestmen possess several key features that differentiate them from the former order. For example, unlike spiders (which have two-segmented bodies, an entirely carnivorous diet, and venom glands), harvestmen are characterized by their single segmented bodies, omnivorous diet, a lack of venom, and (most famously) eight almost comically long legs. Though these arachnids rarely get as large as a dime, one species on Skull Island dwarfs all other extant members of this order; the Colossal Harvestman (Maiacaulos rex).
The Colossal Harvestman is a tarantula-sized resident of the island's semi-desert, where its opportunistic diet proves most beneficial, allowing it to feed on a myriad of organisms (though its preferred food sources seem to be succulent plants and carrion). This arthropod is well-known in the scientific community for its odd species name, which roughly translates to "king of good-mothered plant stalks". The reason for this name comes from two factors; the creature's appearance (its long legs are thick enough to resemble plant stalks) and the behavior of mother members of the species.
After mating, the solitary Colossal Harvestman separate, with the father simply leaving as the mother starts looking after her eggs. The mother (which is larger than the male) will look after her young (many of whom will not survive to adulthood due to hungry hunters) until they reach sexual maturity. Also, though the male is smaller than the female, he is also more ornately colored, sporting orange and green markings as opposed to the female's dull brown and grey coloration.
Author's Note: The Colossal Harvestman is based on the Mother Long-Legs, a massive harvestman-like kaiju from the film Kong Skull Island, though the creature featured in this entry is nowhere near as big.
