Nemerteans use ciliary action in combination with the secretion of mucous to produce a lubricated surface in which the nemertean can easily slither across. This picture shows the mucous trail left behind by the nemertean as it slides along the sediment.

Polycheates use parapodia in combination with muscles and a segmented body plan for locomotion. This Nereis uses its parapodia for crawling and swimming. The parapodia may be modified into paddle-like structures to facilitate swimming or to ventilate tube shafts. Undulatory and peristaltic locomotion is also commonly found among the polycheates.

Gastropod snails such as Battilaria are often found "trail blazing" on the sediment surface. The gastropod is propelled by ciliary motion and wave action of the foot.

The crustaceans found at Garrison Bay include some larger crabs, such as Cancer magister, Cancer productus, as well as a pea crab, Pinnixa sp.  Individuals from each of these species crawl about using their articulated limbs; however, Pinnixa sp. are also known to reside as commensals in the mantle cavities of gaper clams, Tresus capax.

Small nudibranchs like Hermissenda maneuver through the sediment using primarily ciliary motion. They can be found in the lower intertidal zone near boulders.

Other tracks left in the soft sediment are made by a large number species, including terrestrial vertebrates that feed on resident invertebrates.

Polychaete worms exhibit a variety of reproductive strategies, including broadcast spawning, brooding, and the laying of egg capsules. Most polychaetes are dioecious, with gametes stored in the coelom, the large fluid-filled cavity within the body.  External fertilization occurs by releasing gametes into the water, through ducts or by rupturing the body wall (as shown in the picture of the oweniid polychaete to the left).  Nereids and syllids have developed epitoky, where a sexually reproductive worm is produced that can swim and join in swarming events, increasing the chances of successful fertilization.

Bivalves also display a number of different reproductive methods. Tresus capex (gaper clams) typically spawn in late winter to early spring, and sometimes throughout the year.  In contrast, the tiny burrowing Transenella sp. brood their young, at varying development stages, in their mantle cavity, and release small juveniles in the summertime.

Sea anemones (Phylum Cnidaria) exhibit different patterns of asexual reproduction.  Some species undergo fission, where one individual will split into two individuals The large frilly anemone, Metridium, observed in abundance in the bay attached at the pedal disk to bits of shell material, display an interesting form of asexual reproduction where new individuals will bud off from the pedal disk..

Subsurface deposit feeders ingest sediment as they burrow, absorbing any nutrients that the surfaces of sediment particles, and then recycling them.  Many polychaete worms, such as those of the families Arenicolidae and Capitellidae, are subsurface deposit feeders. Arenicolids construct U-shaped burrows in which they generate water currents by two mechanisms. First, peristaltic body contractions can be used to actively pump water through the burrow.  Second, buildup of fecal material at one burrow entrance can aid generation of a pressure differential between burrow openings, a la the Bernoulli principle.  Piles of "cleaned sediment" are common near burrow entrances.

Surface deposit feeders collect food particles directly from the substrate surface. This process is more selective than subsurface deposit feeding because individuals can more easily choose which particles to ingest.  The polychaete families Oweniidae and Terebellidae are surface deposit feeders that are largely sessile, inhabiting vertical tubes that they construct out of mucus/sand or mud.  Individuals extend tentacles out of the tube entrance to collect particles from a position of relative protection. When the tentacles are retracted they carry food to the mouth. Watch the movie of a feeding terebellid!

Filter/suspension feeders at Garrison Bay include a number of bivalve species (e.g., Macoma spp. and Tresus capax), brittle stars (Amphipholus squamata ), and a few small crabs (Pinnixa sp.).  Bivalves use extensions of the mantle, called "siphons," to draw water into their body cavities. Then, they collect particles on the ctenidia, specialized gills that are used for both respiration and food collection.  Brittlestars use their arms, or "ambulacrae," as filtering devices. Pea crabs (Pinnixa sp.) live inside the mantle cavities of gaper clams, taking advantage of water currents created by the bivalves to collect diatoms and detritus.

Siphons of the large filter-feeding "gaper" clam
Tresus capax

Predators and scavengers are not especially diverse at Garrison Bay. This is not due to scarcity of prey, but, in all likelihood, to the inability to locate and successfully capture prey in fine sediment. The large crabs Cancer magister and Cancer productus, with their formidable claws, are common at the surface.  Infaunal predators include the nemertean worm Paranemertes sp., which uses its eversible pharynx, armed with a sharp poisoned stylet, to harpoon and stun prey. Some drilling predators such as gastropods are rarely seen, but evidence of their presence is abundant in the form of drillholes in dead shells. Scavengers in the mud include polychaete worms, such as members of the families Nereidae and Phyllodocidae, that swim in search of dead organic material.

Shell adaptations such as a thick nacreous layer, a high-spire, and shapes that facilitate suction onto a substrate are found at Garrison Bay.

The thick nacreous layer improves the relative hardness of the shell by aligning the CaCO₃ crystals into a cross lamellar pattern that is most resistant to crushing by predators. Increasing the hardness of the shell provides an advantage to predators such as crabs and sea gulls.

Battilaria sp. has a high-spired shell. This shape may allow these animals to retract further into their shell upon encountering predators. On the other hand, limpet shells are dome shaped, which greatly enhances the ability of the animal to clamp the shell to a substrate using the suction of the muscular foot. This prevents predators from lifting the shell and accessing the vulnerable soft tissue.

Battilaria sp.

Lottia pelta