Dryopoda

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  • Phylum Mollusca
  • Class Cephalopoda
  • Order Octopoda
  • Suborder Dryopoda

Origins

The mangrove swamps of the Iredjolsith have produced many strange creatures, since they have never been connected to any other continent, and so they are populated only by animals that have reached it across the ocean, by swimming, floating, or flying. With such an unusual starting complement of animals, many of them have been able to expand into niches they could never have competed for in the presence of continental animals.

One of the odder of such groups is the dryopods (Suborder Dryopoda), the tree-climbing octopods. Many species of octopods can survive short periods out of water, before their mantle cavity collapses, suffocating them; or their skin desiccates. Most often they endure this to chase crabs. And as small crabs took to the mangrove trees, one branch of octopods developed the ability to survive longer periods out of the water, and followed them. The octopods in the warm, murky (and so, poorly oxygenated) water around the mangrove roots were also independently selected to be able to breathe out of water to supplement oxygen intake, even in purely aquatic forms.

These dryopods became adapted to a less aquatic lifestyle, though only as adults. Their eggs are still laid in the water, and the young spend the first, larval stage of their life as part of the plankton. At a certain point in their growth the young start developing the adult traits that allow them to survive out of the water and in the trees. The mantle wall is reinforced with extra cartilage. Their gill branches (which in all octopods are already safely enclosed in the mantle) develop non-stick proteins; mucous glands develop on the skin to keep it from desiccating in the air; and, in many species, the sucker pads on the undersides of the arms, which function poorly out of water, are reduced or transformed into gripping ridges to aid tree-climbing.

Family Neodryopodidae

Dryopods are subject to drifting while in their planktonic larval stage, and some are caught by ocean currents and taken far from the shores they must return to in adulthood to survive. Many of these simply die, evolution having left them no longer able to function as fully aquatic animals in adulthood. Others are taken all the way to other shores, but ones without the mangrove environment that dryopods are adapted to. Some of these nonetheless had environments moist and shaded enough that some dryopod species were able to establish themselves.

But some dryopod larvae drift northwest to the (trans-Edgewall) mangrove shores of the Hajasith, where they encounter an environment familiar in many respects, but with a few critical differences.

On the broad, flat continental shelf, ichthyosaurs are replaced by elasmosaurs as predators of the open waters, but this substitution of one large, lethal predator for another makes little difference to a dryopod. With a entire continent behind them, the open shallows are well supplied with wading birds, ready to make an easy meal of a small octopus floundering in the mud flats, but this was likewise a threat different only in magnitude, not kind, to the threats dryopods had evolved to meet on the Iredjolsith. The critical difference was the presence of monkeys, both as predators on the slower moving dryopods, and as already established competition, preying on the small tree crabs that are the staple of most dyropods.


Most of these accidental colonists, then, never establish any lasting presence. Monkeys waited for them in the trees and birds in the flats. Elasmosaurs in the deeper waters cut off any possibility of them re-adapting to an aquatic life continuing to adulthood. Predatory fish lurked among the mangrove roots, in all sizes the constricted spaces allowed. So the possibility of the dryopods colonizing a mainland already well stocked with terrestrial vertebrates were slim.

But one group of dryopods did manage to establish themselves through a set of extreme adaptations. The young grew as large as was possible without becoming prime targets for the elasmosaurs and wading birds, then they entered the adult phase in phermone-synchronized groups, and left the water for the trees. At this point they underwent a rapid growth phase that took them through the size range in which they were most vulnerable to monkeys as quickly as possible. By remaining in large groups during this pahse, the adolescents made sure that, though many were still taken by monkeys, enough survived for a viable population. This group of dryopods is classified as family Neodryopodidae.

This strategy worked best in and around the large bay in the middle of the mangrove shore of the Hajasith, as a place were the young could be fairly proof against being too dispersed by ocean currents to form crèche groups for the adolescence.

Since the young were forced to be in large groups during the adolescing period, this branch of the dryopoda became more social than most other octopods, though octopods were well pre-adapted to this need, already being among the most intelligent and emotional of non-vertebrates. In some species, these crèche groups started coordinating hunts to fuel faster growth spurts through the dangerous period. Coordinated hunts created an adaptive push towards more complex social behavior, which in turn spurred greater intelligence. The final result of the trends in this lineage are the dryads.


This article has Design Notes: Dryopoda/Notes

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