Observations by dominickdickerson

3 individuals seen swimming off dock at FHL. Dendronotus iris and it’s cousin dendronotid Melibe leonina exhibit similar swimming patterns, consisting of repeated left-right flexions of the entire body. In Dendronotis iris the elaborate papillae that branch from the mantle sway gently around the organism giving it the sporran right of some submarine ribbon dancer.

Collected off FHL dock.

Note the greatly expanded oral hood which the Melibe uses to ensnare it’s prey, swimming crustaceans. The slug grasps a surface , eel grass and bullkelp being common and can congregate in groups called bouquets. They then inflate their heads and sway back and forth waiting for their next meal to swim into its trap. The hood closes around it’s prey where it is then presumably manipulated into the esophagus, which can be clearly seen in the first photo.

This Melibe was collected as bycatch from a beach seine at Jackson beach.

Of the dozens of Melibe I’ve collected and seen in my time on the island this one is unique in its spots. Have not found a reference to know color variants in melibe. First impression is that the spot pigmentation is very similar to that seen on Dirona pellucida.

2 organisms, one found on wood dock piling other found attached to dock tire near yellow sponge (presumed prey item. I have witnessed these dorids locomote from one end of a water table to the other and all swarm over to fragments yellow sponge placed in table.

Photo 1: D. montereyensis in motion. Note the extended rhinophores, those antennae like structures at the front of the organism as well as the branchial plume on the dorsal rear. That structure on the back of the organism is a combined gill/anus. Like all members of the so called cryptobranch dorids, these organisms are defined by their ability to completely retract their plume and rhinophores within their body cavity (Crypto=hidden , branch = gill)

Photo 2: D. montereyensis mating. You can see the mantle flap raised where the organisms touch. Beneath there is the gonopore, the opening of the fused female/male combined reproductive tract. Simultaneously hermaphroditic, the organisms inseminate each other.

The stunning Antiopella fusca (formerly Janolus fuscus) Seen on an emersed tire presumably feeding. They seem particularly fond of thecate hydroids, I have observed them feeding in the field and in my water table on several species of hydroids, minute cnidarians that very often have alternating life histories between sessile stalked polyps and free swimming medusae.

Photo 2: Antiopella fusca mating. Note the size disparity between the organisms.

Found swimming at water’s surface mid-day.

Gastropteron spends most of its life in the benthos of silty bottoms only occasionally rising in the water column with its unmistakable flying gait.
In the first photo the organism appears as it would crawling. The “wings” of the organism are enlarged parapodia that wrap over the body or visceral hump of the organism. Gastropteron takes the leading edge of one parapodia and the trailing edge of the other creates a snorkel for itself, allowing the organism to forage without emerging from the mucky bottom where it roots around for its prey. Dietary information is scarce but it is presumed they consume foraminiferans and annelids within the sediment.