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 photos copyright John P. Hoover unless otherwise credited

Some interesting sea anemones & zoanthids not in Hawaii's Sea Creatures

The following Bishop Museum list of Hawaii species is available online:

Anthozoa (corals, anemones, zoanthids)

Ceriantharian 1 (possibly genus Isarachnanthus)
Photos by Cory Pittman. Cory writes: This is probably my favorite local anemone. :-) I first saw one when it was pointed out to me by another staff member during a class in 1986. And, I've been watching them ever since.

It lives in tide pools and, occasionally, in the shallow subtidal favoring sites with moderately high water movement. In tide pools, the tubes are anchored in sand-filled crevices. The disk diameter is usually around 20-30 mm and the tentacle length is 2-3 times the disk diameter.

The body and marginal tentacles are transparent. There are superficial, basal brown spots on the outer faces of the marginal tentacles and narrow white collars above the spots. When photographed with a flash, it appears substantially more opaque than it does when viewed with the naked eye. By eye, looking down at a tide pool, the body and tentacles are glassily transparent and the white pigment is far less prominent (angle of view and light intensity effect the appearance). So, what you first notice is "a little ring of brown spots floating in mid-water."

It's retraction response varies in speed from night to night, perhaps due to salinity or temperature changes in its pools. But, on a fast night it's extraordinary even for a ceriantharian--right at the limit of what can be perceived by the human eye. So, it "disappears" with barely a flicker. I doesn't retract when touched gently with an inorganic probe. But, at the slightest touch of a finger it's "gone." One time,when I was watching a pool with a line of them in the same crevice, I touched the one on the end triggering retraction. Without further disturbance, the next one in line retracted some second later, then the next one went after a few more seconds. And, that continued through the whole line of 5-6 animals. Presumably, they were responding to something diffusing through the water. I don't know whether I had an irritant on my hand or if retracting animals sometimes release a "signaling" compound...

It extends its tentacles only at night and will sometimes also retract them if a flashlight beam is held on it too long. However, when responding to light, it retracts much more slowly than when responding to touch--just gradually folding them in.

Like many anemones, they're fairly long-lived. I've been watching a couple of clusters in tide pools ever since 1986 with no evidence of significant changes through about 2015--I haven't been back for awhile...). And, there was one isolated subtidal animal near my "night float entrance" at Olowalu that I first noticed in 2000, last photographed in 2012 and last saw sometime around 2015. There was no appreciable change in size over that period.

They appear to feed, primarily, by catching small planktonic animals with the marginal tentacles, then transferring them "one at a time" to the labial tentacles.

The attached photos are all of the same individual taken at different times and at different angles. The first is of the whole animal taken at a slight angle. The second is a closeup of the disk cropped from that shot. They illustrate prey transfer. The third was taken looking straight down and illustrates how the markings change in appearance with the viewing angle. The fourth is a side view. All the photos are mine and were taken at Olowalu.

Joe Rowlett lists it as an undescribed Isarachnanthus in his new book, Indo-Pacific Corals. He also says it can reproduce by transverse fission (with a photo illustrating the process) and has a photo of one that's taken a small fish indicating that it may occasionally eat larger prey.

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Ceriantharian 2 (possibly genus Arachnanthus)
Photos by Katherine Shepherd, Maalaea Bay, Maui. Cory Pittman writes: This is the one that was recently photographed by several people while recording the feeding behavior of Dermatobranchus rubidus and Cerberilla sp. #1. It appears to be very common in silty sand at depths of 20-30ft. Katherine Shepherd just got photos of one from 11 ft and I think there are a couple of fuzzy images of them in the backgrounds of my old photos from the trough at Olowalu. So, it's probably common in protected sand basins at shallower depths, as well.

The tentacles remain extended during the day. However, it's inconspicuous due to its small size. The disk diameter is only 2-4 mm with tentacle lengths of about twice the disk diameter. The marginal tentacles have alternating patches of brown and superficial-white pigment confined to their upper surfaces (unlike in the larger Isarachnanthus bandanensis in which the tentacles have complete brown rings on a cream background). There's dark-brown pigment between the bases of the marginal tentacles.

Joe Rowlett suggested that it's an Arachnanthus in e-mails and on i-Naturalist.

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This unidentified sand-dwelling anemone was photographed on July 26, 2021 in Maalaea Bay, Maui. The top photo is by Kevin Roe and the bottom 2 photos by Rebecca Bicker. All images were taken on the same dive, but the bottom two images might not depict the same individual as the top image.

The animal in the photo 2 had just consumed a nudibranch. Rebecca writes: I was watching a nudi floating in the water column. I was thinking it was alive (probably not) and waiting for it to land in the sand. Instead it floated within the grasp of a nearby anemone and was promptly consumed. Cory thinks the nudi was Baeolidia salaamica. Photo 3, taken before photo 2, shows the anemone in the process of eating the nudibranch.

Rebecca has posted more photos of the nudibranch being eaten in the Sea Slugs of Hawaii Facebook group.

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Palythoa sp.

Mike Rudenko photographed this zoanthid at Crystal Cove (1/2 mile north of Kawaihae harbor, Big Island) in April 2019. He writes: "It was about 2" tall, found in a protected little puka in the satellite reef in the sand. Depth was 45 ft." I sent the photo to James Reimer, an expert on zoanthids, and he replied:

Yes, this is Palythoa of some kind - and a nice image! The two rows or cycles of tentacles plus nice dorsal directive give it away.

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pelagic Anthopleura

April 5, 2017
Cory Pittman writes from Maui:

Today, at Airport Beach, one of our staff (Mitch Olsen) brought back a piece of plastic debris covered with anemones and Lepas. I think this may be the same pelagic Anthopleura I've see a couple times before. It looks like Anthopleura artemisia as illustrated here:

http://bodegahead.blogspot.com/2014/09/a-mouthful-for-moonglow.html

That one's supposed to be benthic. But, it may be "getting around" on debris... The columns had a few grains of adherent sand (the piece of plastic had become overloaded and sunk to the bottom though it was still moving about in the surge). Also, another floating piece with anemones was seen by others during the session.

I've attached a photo of the disk of one of the larger ones (about 20 mm in diameter) and a photo of a couple smaller ones with Lepas and sand grains.

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unknown edwardsid

Divemaster Kelleen at Kohala Divers in Kawaihae noticed this unusual anemone at a depth of about 45 ft. in a fissure along at the base of a rocky wall. It was maybe an inch across. It retracted into a crack when touched, but opened again fairly soon. I sent this photo to Dr. Daphne Fautin who replied:

"This is likely to be another edwardsid. It is very much like dramatic animals from Indonesia and environs ... What makes me think it is an edwardsid is the size, the fact it is a burrower, its sensitivity, and the number of tentacles."

Daphne then forwarded the image to Meg Daly, the world authority on edwardsids. Meg replied: "I agree that this looks like an edwardsiid, and confirm that more than that is impossible without the animal in hand! The color is striking, and reminiscent of the Edwardsianthus pudicus we collected in Oman. Of course, as most edwardsiids are described from color-less preserved material, I have no perspective on how common this coloration is--it may be that multiple species have this (lovely blueish) color."

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Corallimorpharian
Corynactis sp. 1

Sharon Williams photographed this anemone-like animal in a completely dark underwater cave on the South Kona coast of the Big Island in November 2012. Its disc was about 3 inches across. This was an exciting find! I sent the photo to Dr. Daphne Fautin at the University of Kansas. She replied:

I would say this is not an anemone -- it is a corallimorpharian.

There are occasional images of this sort of animal in all manner of places. Most of the tropical shallow photos are taken at night -- so life in a cave is perfectly compatible with it.

Anyway, I would put this among the tropical, nocturnal forms of *Corynactis*. We have no idea how many species there are. Too few data.

A very small and inconspicuous Corynactis species, less than half an inch across, occurs under dead coral at wading depths in Hawai`i (see Cory Pittman's photos below), but as far as I know, Sharon's photo is the first record of a large one in in the Islands. Given the difference in size, habitat, and a few other details, it would appear to be a species distinct from the small one. This animal appears to be extremely rare. If you see another one like this in Hawai`i, please let me know!

Note: In some books, larger Corynactis like these are listed under the genus Pseudocorynactis; according to Dr. Fautin that genus is now considered invalid. Paul Humann and Ned DeLoach's Caribbean invertebrate book gives the common name "Orange Ball Corallimorph" to a similar species commonly seen in the Caribbean.
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Corallimorpharian
Corynactis sp. 2

With regard to Corynactis sp. 2, above, Cory Pittman writes: "I've found similar animals several times under rocks at Kapalua Bay that I've been calling Corynactis. I've attached photos of a few. They're small and inconspicuous but apparently not uncommon at the site. I don't know whether they're the same species as the one from the cave..." Cory's animals are very likely the same as those descibed from Oahu on p. 130 of Reef and Shore Fauna of Hawaii, Section 1 (B.P. Bishop Museum Special Publication 64-1): "This species is usually colonial, consisting of a large polyp to which several smaller ones are connected by fleshy stolons. Large polyps have both heights and diameters of about 10 mm. The seventy-odd tentacles are radially arranged and bear acrospheres at the tips. The column is orange brown; the oral disk and tentacles are mostly transparent; and the acrospheres are opaque white to pale orange brown."
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Tube Anemone?
Cerianthus? sp.

John Earle found this anemone off Waikiki, Oahu. " ... out from "100' Hole" dive site along drop from 110 to around 130', date 8/26/2012, Size of "head" part around 3-4" diameter." It looks like a tube anemone, possibly of the genus Cerianthus. It would be impossible to know the genus for sure from a photograph alone.

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Heteranthus verruculatus Klunzinger, 1877
family Phymanthidae

Cory Pittman photographed a colony of these anemones in Kahului Harbor, Maui. I sent the photo to Dr. Daphne Fautin at the University of Kansas, who kindly identified it for us. According to Reef and Shore Fauna of Hawaii, Section 1 (published in 1977), "The oral disk is dark greenish brown to sepia, overlaid by varying amounts of opaque white, the white sometimes covering all the disk except the mesenterial insertions.... In Hawaii, this species is known only from Coconut Island in Kaneohe Bay, Oahu, where it occurs on sills of concrete spillways between fish ponds."

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Actinoporus elongatus Carlgren, 1900
family Aurelianidae

Mike Ogata at the Maui Ocean Center emailed me in May 2008 about an unidentified anemone found in Maalaea Bay which was on display in one of their aquariums. Later, Cory Pittman visited the aquarium and snapped this photo of it partially emerged. He thought it might be about 2 in. across. I sent the photos to Daphne Fautin at the Univ. of Kansas who identified it tentatively as Actinoporus elongatus, first found off Mozambique, East Africa and known also from Madagascar and near Townsville, Australia. Examination of a specimen would be needed to confirm the ID, but Dr. Fautin seemed fairly sure. The Maui Ocean Center specimen was found in about 20 ft. in silty sand. Definitely a first record for Hawai`i.

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undescribed species in genus Mesacmaea
family Haloclavidae (previously listed here as family Edwardsiidae)

I found this small anemone in silty sand at Ho`okena, Hawaii, at a depth of about 50 ft. in Sept. 2008. It was probably not more than an inch in diameter and disappeared quickly into its hole after I snapped the photo. Because of its quick withdrawal I thought it might be a tube anemone (cerianthid). I sent the photo to Dr. Daphne Fautin, anemone specialist at the Univ. of Kansas, and she says it is definitely not a cerianthid because it has no tentacles around the mouth. She said that it's an edwardsid and belongs to a family of anemones which live in sand. They tend to be similar in appearance and often hold a few tentacles erect. Because of their sensitivity they are very hard to collect. Without a specimen, of course, she cannot go further. At least two species in this family are known from Hawaii, both from shallow water close to shore. This may be a third.

In March 2013 I received the following from Karen Sanamyan in Russia. http://actiniaria.com

Today I visited your website, a page with photos of sea anemones.
They all are really great and, that is important, it shows species which
are not commonly photographed.

I have some comments on one species from your website (the photo is
attached). On your website this photo is labelled as an "anemone
belonging to a family Edwardsiidae". Actually this is not an
Edwardsiid anemone, all edwardsiid anemones look very differently.

Actually this anemone belongs to another family, this is a species of
the genus Mesacmaea (family Haloclavidae). Note that the species on
your photo has tentacles of the first (inner) cycle held inwards over
the disk and hiding mouth. The specimen is bilaterally symmetrical and
the directive tentacles are different (I marked them by blue dots on
the photo) - one directive tentacle is short and belongs to the first
(the inner) cycle, and another directive tentacle (left on the photo)
is long and belongs to outer cycle. These characters are very
distinctive and not occur in any other genus of sea anemones. So I'm
absolute sure this is a member of the genus Mesacmaea.

Now about the species. Currently the genus contains only one proved
valid species Mesacmaea mitchellii. There are several other species
formally assigned to this genus in 18xx, but these very old imperfect
descriptions may actually apply to almost any burrowing anemone - this
is why I say that Mesacmaea mitchellii is the only valid species of
the genus. This species is known from Europe only and it has more
numerous tentacles than your species. So, I'm sure, you have an
undescribed species of Mesacmaea.

In July 2013 Paul Okumura sent me the two photos below, showing one of these anemones eating the tiny yellow sand-dwelling nudibranch Siphoteron quadrispinosum. Paul writes:
I saw this today. My strobes were not fast enough to catch the strike, but you can see the siphopteron inside the anemone. I was pretty stoked, and thought you might enjoy. @Jail House Rock in 74' of water.

photos by Paul Okumura
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Below are four unidentified anemones I photographed in Ma`alaea Bay, Maui, in 2008. Depth was 20-30 ft. The substrate is silty sand and mud. I sent the photos to Dr. Daphne Fautin of the University of Kansas. Her brief comments below.

#1 seems to be an actiniid anemone -- but without being able to see the column, I cannot tell. Likewise anemone 3."

"Anemone #2 looks as if it burrows in mud and it definitely has acontia. Meg Daly and Roger Goodwill just described a new species of anemone from Laie that this may be."

see: Pacific Science 63(2):263-275. 2009 Andvakia discipulorum, A New Species of Burrowing Sea Anemone from Hawai‘i, with a Revision of Andvakia Danielssen, 1890
Marymegan Daly and Roger H. Goodwill

However, upon seeing the photos (July 2013) Roger Goodwill says he doesn't think these look like the anemone he described with Meg.

"... seems to be an actiniid anemone -- but without being able to see the column, I cannot tell."

The three photos above were taken by Cory Pittman at Hekili Point, Maui, in April, 2013. There were several hundred anemones (largest about 7 mm across) attached to a floating plastic bin lid.

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genus Nemanthus

Sam Kahng sent me this photo of unidentified anemones found attached to black coral at 140 ft. The shot was taken at the Waikiki Aquarium. Dr. Daphne Fautin writes: "This photo shows what are generally called *Nemanthus*. They are common at moderate depths attached to rods (usually octocoral branches, but also probably any other elongate cylinder). They are photographed by divers because of their spectacular colors, but are rarely collected so their identity cannot be ascertained. There are a couple of other genera that seem similar and that are easily distinguished by a glance inside (*Nemanthus* has "acontioids," which are superficially similar to acontia but are really very different). They are known from eastern Asia and the Gulf of California, so Hawaii is not at all surprising." I believe this is another first record for Hawaii.
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family Aliciidae
Kendra Choquette of Dive Makai in Kona sent in this photo. She writes:

We saw this critter in 100 feet of water, attached to a rock, out in the middle of the sand at the Garden Eel Dive by the airport! I touched it (of course) and it did NOT pull in but I could see it was attached to the rock. It also mildly stung me. Gotta be an anemone of some sort. The strange creature was the size of my fist-maybe 5-6 inches across and 3-4 inches vertically. Any ideas????

I forwarded Kendra's photo to Dr. Daphne Fautin at the University of Kansas who replied that it belongs to an anemone of the family Aliciidae. These anemones, she writes, have protrusions on the column that harbor symbiotic algae. Because an accurate ID even to genus can only be made by examining the form and placement of the protrusions on the column, Dr. Fautin was unable to identify it further.

Anemones in this family, like many others, tend to contract by day and expand by night. It would be terrific if Kendra could do a night dive at the site and photograph it in its expanded form. Maybe Dr. Fautin could then identify it for us. These are amazing, beautiful animals when expanded, and much sought-after by underwater photographers in the know.

You can find still more images by searching Google. Anemones of this family, often called "Berried Anemones," are rarely reported from Hawai`i. This is a very exciting find. Go Kendra!

Update: in October 2021 Kevin Roe sent me his photo of a beautiful expanded specimen clearly showing the "berries" on its column. It was found by his dive buddy David Fuller during a night dive in a Halimeda bed on the south side of Maui There's no way to know whether it's the same exact species as Kendra's find above, but it is certainly in the family Aliciidae.