|Barycypraea teulerei LIVE|
BARYCYPRAEA TEULEREI, GOING BACK TO THE RECENTLY DISCOVERED NEW POPULATION.
Fig. 1. Barycypraea teulerei on site, South Oman. New living population.
As you might remember, last year, during my usual trip to Oman, I discovered a new living population of Barycypraea teulerei1. This year I went back to the same place, equipped with a camera (photo and video) to collect more information about this beautiful species (Fig. 1).
This time I planned the trip quite accurately, because the site is not very easy to reach and we wanted to spend at least some days there to get some good pictures and to observe the animals as carefully as possible. To do that, it was important to be in the place during low tide hours. The first day, after reaching the spot, we saw that the sandy/muddy ground was essentially unchanged and it was even more rich in flora and fauna than the past year. This was a good start, and we soon realized that the population was numerous and in good health! Between our two travels, probably nobody was there, except for few fishermen, whose interests are very different from observing and, even less, collecting this shell.
We soon noticed that many specimens of teulerei were hatching their eggs (Fig. 1). All of them were attached upside down to a valve of a dead bivalve, which I will call the‘nest valve’ (Fig. 2). The shape and size of the hatching specimens were very variable. The size of the‘nest valves’ were very variable too, and apparently unrelated to that of the shell: we saw some shells totally covered by a large‘nest valve’, whether some other big specimens were using a little“nest valve” that covered only a part of them. I had to flip the valve to take the picture of the hatching specimen, but of course after taking the picture, I flipped the valve back to its original position.
Fig. 2. Barycypraea teulerei on site, South Oman. Specimens on the ‘nest valve’.
Another interesting fact is that we frequently found some other teulerei nearby the hatching specimens, and I’d suppose they are males (Fig. 3, 4). In one occasion I was able to take a picture of a male fertilizing the female while she was already on her nest valve. This was the only case in which I did not find the hatching specimen upside down, covered by the nest valve. As I already wrote in my previous article in Beautifulcowries magazine1, the hatching specimen is always firmly attached to the valve, so it is difficult to remove it because the foot acts like a sucker. We also found a couple of specimens already attached to their valves, but they didn’t have their eggs yet. Probably they still had to lay eggs, and maybe they were waiting for one male to fertilize them. Does the fertilization begin before the eggs are laid, or is it a simultaneous process? Maybe the male stimulates the female to spawn during mating. I don't have direct observations to answer this question, because I did not want to disturb the laying specimens in their ‘nest valves’ while mating, to check whether the eggs were already laid or not!
Fig. 3. B. teulerei males approaching the hatching female, covered by the nest valve).
Fig. 4. B. teulerei males approaching the hatching one. Note the fertilizing male (see also Fig. 5 for a close up).
Fig. 5. A Barycypraea teulerei male specimen fertilizing the female on the ‘nest valve’ (same specimens of Fig. 4).
The eggs, or maybe more accurately, the egg capsules, are produced in clusters (Fig. 6). Each egg capsule contains a few dark brown eggs. Since teulerei is a direct developer, a single young shell will hatch from each capsule, crawling away. In fact, only one egg will develop into a young mollusk, while others will be used as food. In the pictures we could see different stages of evelopment. I also show here a closer picture of the capsules, in which we can notice that the developmental stage is quite advanced.
Fig. 6. Barycypraea teulerei egg capsules
Normally all teulerei are very static. They rarely move around and when they do so they are very slow, slower than many other species of cowrie. All their movements are as such, including mantle exposure and retraction. This is probably due to the fact that they don't seem to have many predators during their adult life, or maybe they don't have predators at all! In fact, they don't look for any shelter or hide. They only hide during the hatching period, when they seem to be more vulnerable and they repair themselves under the ‘nest valve’, flipped upside down. It is unclear whether they hide to protect themselves and their eggs from possible predators, or if this is just a way to shelter their eggs from direct sunlight. Anyway, we couldn’t find any specimen with damage signs that could be caused by predators!
Unlike in the past year, we were able to observe more specimens with a totally or partially exposed mantle and to take many pictures of them (Fig. 7). The thickness of the mantle is quite variable, but it is normally very thin and almost transparent. So, you can always see the shell under the exposed mantle. In some cases the shell seems slightly dull, but, once giving a closer look, you soon realize this is because of the mantle.
Some stats on the Barycypraea teulerei population :
We had seen hundreds of specimens during the three days we were on site. So we had the opportunity to collect relevant statistical information (also considering the specimens observed in the last year too). Shell shape is very variable: some specimens are depressed, others are more inflated. The ratio between length and width is more constant.
The pattern is very variable too. Some shells have a small blotch on dorsum, often partially covered by the lateral pattern. Some others present a large, fragmented or divided blotch. Some others again have a groove in the middle of the dorsum. We rarely found shells with relevant growth lines or other kind of damages like scars, breaks or drills. Inclusions are also rare. ‘Water spots’ on dorsum are more frequent instead.
Juvenile specimens were quite rare. Maybe the juvenile specimens are more hidden then the adult ones, or they live at different bathymetric levels. About the bathymetric distribution of teulerei, we found it uniformly distributed from 0 to about 50‐70 cm of depth, but we could not see anything deeper because the water was very muddy. So we don't know what is the deeper bathymetric limit of this species.
In the same habitat, along with teulerei, we found some more cowries species. Erronea caurica quinquefasciata was rare, but one specimen was hatching eggs too (Fig. 8). On the contrary, Naria turdus (f. winckworthi) (Fig. 8) was very common and this species was by far the easiest to find in every low tide flat and rocky puddle I have browsed in Oman!
I finally list the averages data for the shells we have collected:
Fig. 7. Barycypraea teulerei live specimens in their environment.