Bubbles from the Naturalist Jerry's tank - by Jerry Ligon

December 2006: Armina nudibrach, revised

The armina nudibranch (photo: Marge Lawson )

Marge Lawson, a lady I described in an earlier "Bubbles" article as having Attention Surplus Disorder because of the attention to detail that she possess which allows her to find such rare creatures on Bari as Coral Scorpionfish, several members of the pipefish family, and yellow-faced pikeblenny, has struck again.  This time by finding a nudibranch that is still puzzling the experts as to exactly what species it belongs.  She spends part of the year with her husband on Bonaire and owns a condo at Sand Dollar.  In her own words is the following narration describing  her most recent manifestation.

In early October I was coming in from a dive when something beneath the sand caught my eye. There was a fair amount of surge that day, and as the surge washed sand back and forth I caught a glimpse of black and whitish-yellow stripes. I took a few pictures, and then gently dug my hand into the sand beneath the nudibranch and lifted it to the top of the sand where I quickly took a couple more pictures before it dug back down into the sand. I found it in the same general vicinity (80 to 90 yards north of the Sand Dollar dock at 10 foot depth) for the next two days, and showed it to several friends. It was always mostly buried in the sand with just the little pink sensors and a little of the back visible. At first I thought it might be a Smiling Armina nudibranch, but after thinking about it for a while I decided that it lacked two identifying characteristics of a Smiling Armina: the stripes didnt go all the way down the back (it had a smooth pink spot in the middle of the back), and it lacked a 'smile', although it had a few small black spots in the smile area.

A few weeks later I found another Armina about 100 yards south of the first Armina. It didnt look very healthy, and was completely exposed. The stripes were less distinct, and it had some symmetrical bald spots on either side of the stripes that went all the way down the middle of the back. A couple days later I found it with the tail buried in the sand and the rest of the body flopping back and forth with the surge. I could tell it was still alive since it moved a little every once in a while. It didnt surprise me when I found it upside down on the sand the next day, very obviously dead, with small bites taken out of the sides.

A couple weeks after that, I found a third Armina approximately half way between the other two Arminas. All I saw was the tip of the tail as it was digging down under the sand. It disappeared completely before I could show it to a friend. I kept looking in that area for a few days, and finally found it again. I watched it for about 1 ½ hours and saw it come completely out of the sand three times, change direction slightly, then after a minute or two, disappear under the sand again. During the next few days I was able to find it most of the time, although all that was usually visible was the very tip of the tail and the little pink sensors. It also had some symmetrical bald spots down its back, but appeared to be healthy.

Shortly before leaving Bonaire, I found a fourth Armina that was obviously not healthy. It was lying on top of the sand and didnt move much, even when the surge flopped it upside down. The stripes went all the way down the back (unlike the others, which had bald spots), and instead of black spots in the smile area, it actually had a solid black smile.

All of the Arminas were about the same size (about 1¼ inches long) and were found in the 10 to 12 foot depth, but some of the markings differed. The stripe down the front of the face varied from a solid V shape, to a broken stripe, to a solid stripe, and the 'smile' varied from a few small dots to some large spots to a fairly solid smile. Also, the stripes down the back varied not only in how distinct they appeared, but also whether they were broken with bald spots.

After finding the second Armina I did some research on the internet and found a website called Sea Slug Forum, which is hosted by Dr. Bill Rudman of the Australian Museum in Sydney, Australia. If youd like to see my posting and additional pictures and his reply, click on http://www.seaslugforum.net/find.cfm?id=18388 and http://www.seaslugforum.net/find.cfm?id=18566.

He thinks the Arminas might be Armina Wattlas, but said it is difficult to tell for sure since so little research has been done on nudibranchs and many of the descriptions are based on preserved specimens. He said Arminas are nocturnal creatures and are not usually seen during the day, and thinks the lack of stripes down the back were caused by bites, which were likely caused by the Arminas not being buried under the sand during the day. Dr. Rudman said I was probably finding them during the day because they had been bitten and were not exhibiting their normal behavior. That would explain the first three Arminas, but the fourth Armina didnt have any bite marks, and yet was obviously dying. That makes me wonder if the Arminas were at the end of their life cycle or suffering from a disease, which caused them to not bury themselves in the sand during the day. Being exposed, some of them were bitten.

It is very interesting that Ive done hundreds of dives on Bari Reef (plus many other dives elsewhere on Bonaire) during the past 3 years and had never seen an Armina before, and yet found four of them within a 6 or 7 week span. Ive talked to other divers, including Jerry Ligon, the Bonaire Dive and Adventure Naturalist, and none of them had ever seen an Armina before. Perhaps the currents brought a number of Arminas to Bari Reef this year so they were fairly abundant, or perhaps theyve always been there, but until I saw the first Armina I didnt know what to look for and possibly passed by them without noticing them. Its also interesting that their normal food, Seapens, is not available on Bari Reef, although a related food, Sea Pansies, is fairly abundant in the area where I found the Arminas.

In addition to the Arminas, Ive also found a couple of Purple Crowned Sea Goddesses on Bari Reef, and earlier this year I found a nudibranch that belongs in the Sea Goddess family, but didnt match any of the pictures in the Reef Creature Identification book and is so far unidentified.

Back to top