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This is Pagurus venturensis (Ventura hermit),
a much
less common hermit crab than P. samuelis (blueband hermit) in southern California.
P. venturensis
is similar in appearance to another more northern hermit crab, Pagurus hirsutiusculus (hairy hermit),
which is very common from central California to Alaska.
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Lottia gigantea
(owl limpet) with barnacles and limpets (mostly L. conus) on its shell
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an upside down Ophionereis annulata (banded brittle star)
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juvenile bat star (Patiria miniata)
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This is probably the most common sipunculan (peanut worm) we see in southern
California, Themiste pyroides. Sipunculans used to be placed in their own phylum but are currently
classified as belonging to Annelida, even though they are unsegmented unlike most annelids.
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Here, the sipunculan is next to
a conspicuous chiton, Stenoplax conspicua.
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To feed,
a sipunculan inverts its long proboscis known as an introvert. There is a crown of tentacles
at its end that the sipunculan uses to feed on plankton or detritus. Here, there is a blueband hermit
(Pagurus samuelis) in a western banded turban snail shell (Tegula eiseni).
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Lepidozona pectinulata (the pectinulate Lepidozona?) - the tiny snails on
its shell plates and alongside of it are Vitrinella oldroydi, which are more normally found around the tail end of Stenoplax conspicua, likely
feeding on its fecal pellets.
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Phragmatopoma
californica (sand castle worms) are tube-dwelling polychaetes (Annelida) belonging to the
family, Sabellariidae. Underwater, they extend their dark crown of tentacles to catch plankton.
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Stenoplax conspicua (conspicuous chtion)
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Aggregating anemones (Anthopleura elegantissima) divides to form a clone of similar
small anemones that cover rocks in the high-mid zone. Each clone competes for space with other
clones when the tide is higher. The anemones on the edge of a clone lash out to attack anemones
in other clones with tentacles armed with toxic nematocysts. On low tides, they close up and take
advantage of sand and shells to help them avoid desiccation.
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Lottia paleacea (surfgrass limpet)
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L. paleacea grows only as wide as the surfgrass it is found
on, in this case the only southern California species we see, the 1 mm-wide Phyllospadix torreyi. In central California, there is also a
second surfgrass species, the 3 mm-wide P. scouleri, and L. paleacea found on this wider species again grow just as wide as the surfgrass blade,
but about the same length.
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great egret
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Tylodina fungina,
commonly known as the umbrella slug or mushroom sidegill, Monica found stranded out of water
on a very low tide on a beautiful afternoon for us but probably warm for the normally
subtidal T. fungina. It was the first time I have seen this species in southern California,
but I have known about it for a long time. After all, it is on the cover of Myra Keen's classic 1971 book,
Sea Shells of Tropical West America, 2nd Ed., of which I own three copies.
- Keen (1971)
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I put the Tylodina fungina in shallow water, and it took quite a while for it to resume activity.
I came back to in after about 30 minutes and managed to observe it crawling underwater.
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Tylodina fungina
feeds exclusively on a diet of yellow sponges of the genus, Aplysina, and it uses the
nasty sulfur smelly chemicals in the sponges for its own defense. Its bright yellow color helps
advertise that it would have a foul taste to potential predators.
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Pseudopusula californiana (coffee-bean triviid), spotted by Melanie, has recently seemed to be less
common than a larger and formerly mostly more southern, Pusula solandri (Solander's triviid).
I only caught an couple of images at this angle before it got away.
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P. californiana is mostly subtidal and associated with ascidians, but we sometimes find its
shell, again less commonly than P. solandri shells.
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Roperia pousoni (Poulson's rock snail)
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Ophionereis annulata (banded brittle star)
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This T. fungina represents one of only seven accepted species
worldwide for its genus, which is the only genus for the family Tylodinidae, false limpets with
a thin limpet-like shell. This family and another, Umbraculidae, belong to Umbraculoidea,
which is grouped together with sea hares and other sea slugs in Euopisthobranchia. This group
does not include the highly diverse nudibranchs. They are in a separate clade of sea slugs.
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We (see appended link)
included transcriptome data sets from earlier authors for Tylodina fungina and multiple other
Euopisthobranchia species, together as the most proximal outgroup in our analysis of Panpulmonata,
a species-rich clade that includes diverse sea slugs known as sacoglossans, siphon limpets,
some marine snails (e.g., about 10,000 species of pyramidellids), and a huge diversity of
land snails and slugs. Although others use somewhat different names in a similar higher
classification, we found that Euopisthobranchia + Panpulmonata are supported as reciprocally
monophyletic, together as Tectipleura, and this is sister of Nudipleura, which includes the
nudibranchs.
P. Krug et al. (2022; see Figure 1)
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This is a female southern kelp crab, Taliepus nuttallii, but judging from the images at iNaturalist.org,
a more common color is brick red.
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molt from a lined shore crab (Pachygrapsus crassipes)
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The predatory whelk, Mexacanthina lugubris, is a southern species
that was rare or absent in Orange County until the last couple of decades. Now it is very common in portions of the intertidal at Dana Point, and it appears
to be feeding on California mussels (Mytilus californianus).
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Since it arrived from more southern localities along the coast of the Baja California Peninsula,
M. lugribis could be substantially impacting mussel populations in Orange County, and could impact other species as well. The northern range expansion
is likely due to climate warming.
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Porcelain crabs, in this case Petrolisthes cabrilloi (Cabrillo's
porcelain crab), are not true crabs but instead are anomurans related to hermit crabs and their allies. Despite large claws for their body size, they are
plankton feeders.
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Shells of our predatory neogastropods are often infested with coral-like growths of a bryozoan,
Akatopora tincta.
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This shell was from a subtidal species of the genus, Pteropurpura. It might or might not
be occupied by a hermit crab.
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juvenile teguline snail and a chiton, Lepidozona pectinulata
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Under Construction!