Observações de cemills

Thousands (likely millions) of Eutonina indicans hydromedusae came in from the Pacific Ocean in the last few days, here caught in an eddy beside the dock, with especially lots of the spherical ctenophore Pleurobrachia bachei and a large Bolinopsis microptera. Most of the white dots are copepods, also suddenly very abundant near the surface.

Collected in late summer at the surface in Friday Harbor, photographed in an aquarium. Bell diameter was 30 mm. A rare visitor near the end of the season, when there were very few other jellies in the water. See a beached one August 2021 from Homer, Alaska at https://www.inaturalist.org/observations/95334168.

This 7 mm tall early spring species is pretty much of a look-alike for the more-common Proboscidactyla flavicirrata. I had to look at it under the microscope to see that the four radial canals run straight in this species, with very fine arching branches that reach the tentacle bulbs (see second image). In Proboscidactyla, the radial canals branch dichotomously several times. Hand-dipped at the surface and photographed in an aquarium.

This tiny, uncommon, more-or-less adult ctenophore was 4 mm long. The four orangy-red pigment spots are diagnostic. It is also unusual because the pair of simple, unbranched tentacles exit near the mouth, not towards the aboral pole like most cydippid ctenophores. Hand-dipped from the surface plankton and photographed in an aquarium.

An early spring species about 15 mm in diameter. The gonads and canals look bluish some distance underwater, but up close are always a characteristic pale rose-pink that my camera didn't pick up. The edge sometimes rolls up, as in the second image, or more extremely so. Hand dipped from the surface plankton and photographed in an aquarium.

This little ctenophore is about one cm long, with two very fine, unbranched tentacles. It eats primarily appendicularia. It is never very common, and is difficult to see because it is very transparent. It is usually found here in the spring.

Occurs on eelgrass Zostera and surfgrass Phyllospadix in the shallow subtidal, San Juan Islands, Washington and southern Vancouver Island, British Columbia. Assuming for now that they are the same species, they are usually green and on seagrasses in WA and BC and reddish on rock or algae in California. This animal was found about five miles from the type locality for M. handi, on the same island.

Collected by divers in upper 20 m of open ocean and photographed in an aquarium on board the ship. Forskalia siphonophore with lots of hyperiid amphipods on or in the nectophores. Stem and filaments contracted.

Identified at the time by P. Pugh, siphonophore taxonomy specialist.

This is the original drawing by Mertens (1833) of what he called at the time Beroe cucumis, collected in the NE Pacific on a cruise from Sitka to Unalaska on July 25-26, 1827. This species has only rarely been collected in the past 190 years, and typically flat on beaches, so I submit this illustration for comparison with new material.

This little-known pelagic ctenophore was collected on a cobble beach in Friday Harbor Washington on May 22, 1989 by two undergraduate invertebrate zoology students. It was 105 mm long and only one of the two tentacles is in a normal position, exiting the body through the tentacle sheath. The other tentacle seems to have entered the gut through a hole in the wall of the pharynx and is seen here as a white streak, complete with sidebranches, inside the pharynx. Photographed in an aquarium.

I collected a much smaller (9 mm long) individual of the same species three weeks later at the surface in Friday Harbor on June 18, 1989.

Note that I have also uploaded the original pen and ink illustration of this species (originally described as Beroe cucumis) by Mertens 1833 at https://www.inaturalist.org/observations/61758194.

A single Tethys fimbria was collected swimming at the surface of the Bay of Villefranche over deep water and brought into a large holding tank in the laboratory. After a couple of days, it laid this 14 cm long pink, spiral string of egg capsules, attached to the cement wall of the holding tank at just one end by a mucous strand. A second egg mass was not attached at all. Each capsule contained 15-20 eggs; the embryos hatched in about 10-11 days. (Weirdly, it didn't occur to me at the time to photograph the nudibranch!)

These tiny creeping jellyfish were collected in a plankton net thrown from a rocky shore and dragged in over some seaweed, where they had been living. Photographed under a microscope, the larger bell was 0.7-0.8 mm diameter. These micro-medusae live on intertidal seaweed in the surf zone and creep around on their multiple tentacle "legs".
They reproduce asexually by budding off new individuals from the central disk - note about six developing buds on the bigger specimen, with the top two now recognizable as nearly-ready to be freed new jellyfish. The central disk was a tannish golden color, with red eyespots.

A rare find collected wild in Friday Harbor, but this smaller and more fragile Leptomedusa masquerades as just another Clytia gregarium in the spring or early summer. There is a little bit of black around the margin, and I was very surprised that when kept in a bowl for days or weeks, it seems to have reproduced by fission. This probably explains why it has a variable number of radial canals. Photographed in an aquarium. The bell diameter was 10 mm.

Recent hatchling of Enteroctopus dofleini, captured at night in the surface plankton and photographed in an aquarium. Total length about 5.5 mm. Date is approximate.

Distinguished from Octopus rubescens because O. rubescens hatchlings have two rows (paired) of chromatophores running down each arm, while E. dofleini hatchlings have a single row of chromatophores running down each arm.

Recent hatchling of Octopus rubescens, captured at night in the surface plankton and photographed in an aquarium. Total length about 6.5 mm. Date is approximate.

Distinguished from Enteroctopus dofleini because O. rubescens hatchlings have two rows (paired) of chromatophores running down each arm, while E. dofleini has a single row of chromatophores running down each arm.

Single scyphistoma polyp of Aurelia labiata, in the process of strobilation, creating larval medusae that will be released one by one from the top of the polyp. The medusa at the top of the stack, with manubrium and mouth facing upward in this photograph, is nearly ready to release and swim off. Collected wild from under a floating dock, photographed in an aquarium.

Pair of scyphistoma polyps of Aurelia labiata; the individual on the right seems to be beginning the process of strobilation, forming a stack of larval jellyfish that will eventually be released one by one. Collected from under a floating dock, photographed in an aquarium.