Sea Cucumber and Pearl Fish by Patrick Sheehan on Prezi
The symbiotic relationship between Sea cucumbers (Holothuriidae) and Pearlfish (Carapidae). Article (PDF Available) with Reads. But sea cucumbers are their most infamous hosts. Having found one by following its smell, a pearlfish will dive into the anus headfirst. The symbiotic relationship between Sea cucumbers (Holothuriidae) and Pearlfish (Carapidae) Brooke Luciano, Ashleigh Lyman, Selena McMillan, Abby Nickels.
The tail of the pearl fish is long and pointed, and the anus of this fish is located close to its neck. Pearl fish typically grow to be about 15 cm long 4. The female pearl fish releases clumps of eggs late in the summer to begin the life cycle.
These eggs rise to the surface and hatch, turning into a specific type of larvae called vexillifers. These larvae live among the plankton until reaching a length of about 7 to 8 cm.
Themes of Parasitology: Relaxing in the Rectum
At this point, the larvae develop into tenuis. These forms descend to the ocean floor and begin their search for food and a host 5.
The pearl fish will constantly be on the lookout for sea cucumbers to create a symbiotic relationship. Once a pearl fish Onuxodon or Carapus finds a sea cucumber Holothuroideait immediately begins to smell around to distinguish between the head and the anus of the cucumber 6. Once it finds the anus, the pearl fish works its way into the rectum of the sea cucumber, eventually being completely engulfed in the digestive canal of its host.
There it will spend the day inside, using its host as a form of protection. After feeding, the pearl fish returns to its host and waits for the sea cucumber to take a breath.
When the anus opens for respiration, the pearl fish simply swims back inside, seeking shelter in the rectum of its host 8. The pearl fish and the sea cucumber have evolved a symbiotic relationship know as commensalism.
Meanwhile, the sea cucumber appears to be unaffected by this relationship. As far as we know, the pearl fish is not taking anything from the sea cucumber.
The reproductive success of the cucumber remains the same. Therefore, since the pearl fish benefits and the sea cucumber is neither helped nor harmed, one can argue that this relationship is one of commensalism.
Many other organisms have benefitted from relationships similar to that of the sea cucumber and the pearl fish. The pearl fish have also learned to penetrate the bodies of other invertebrates such a starfish, sea squirts, and clams.
A number of crabs and polychaete worms have also evolved to live inside sea cucumbers and have become specialized for gaining protection from the cloaca of that host 9. The relationship between the pearl fish and the sea cucumber is not obligatory, but the pearl fish benefits from its symbiosis with the sea cucumber.
Cucumbers were counted on 5 meters of each side along the 50 meters. We then used the transects to measure the distribution and abundance of the Holothurian hosts. Collections of the two species of Holothurians occurred from Nov 8th to Dec 2nd of Specimens were collected at various depths and time periods throughout the day to examine Carapidae distribution patterns and to be used in our experiments.
The collected specimens were brought back to the lab, placed in salt-water tanks, and observed daily and nightly. Pearl fish were extracted by depleting the hosts of oxygen using a shallow container of water and confining the cucumber in the container until the carapid exited its host.
To test the idea that there was intraspecific and interspecific competition H1we tagged carapidae and its hosts in the lab to observe if competition occurred between the tagged carapidae and different carapidae for hosts. Competition was measured by observing aggressive behavior biting, cannibalism between the same species as well as different species of carapidae.
In order to assess the concept of host specificity H2we tagged pearlfish and placed them in a tank with two or more species of sea cucumber including its present host. Observations were made of the twelve trials on the behavior and decisions of the tagged pearl fish as to what host it decided to enter.Sex on the Reef - Reef Life of the Andaman - Part 24
The presence of association cues between the Holothurians and Carapids H3 was investigated by the following method. The tagged pearl fish was introduced to a holothuriidae host and observations of association cues i. To test the idea that carapids were nocturnally active H4night observations were done to see if the fish really did exit its host for feeding purposes.
Results Intraspecific and interspecific competition between two carapid species for a Holothurian host Intraspecific and interspecific competition was found in both species of carapids. It was found that competition occurred inside the body cavity of the cucumber between several carapids. In one trial, two male E.
Dissection of the host cucumber took place finding one male, one female, and an adult C. Within the stomach of the surviving male E. This was verified in another replication as a juvenile C. Other evidence of competition included bite marks on the specimens used in these trials and on other carapids extracted from collected cucumbers. In one such case, evidence of interspecific fighting between the two species of carapids was observed.
This Fish Lives Inside Sea Cucumber’s Anus
Host specificity of Carapidae in relation to Holothurian hosts After monitoring 12 trials of host preference, the results indicated no selectivity of carapids for their original hosts.
Both species of carapids either entered the first host that they came across or hosts other than their own.
In 12 trials there were only 2 cases in which the fish did find its original host. We performed these trials with 2 adult C. Each fish appeared to smell the length of the body of its potential host, doing lengthy surveys a number of times before actually entering the anus.
Both species of carapids demonstrated this behavior. It was also observed that both species of carapids seemed to listen along the body of the host almost as if trying to detect the presence of another occupant inside. A type of knocking around the anus area was initiated by the fish as a means of encouraging its entrance into the cavity. Nocturnal activity of two species of carapids After one all night survey of a B.
Discussion Many exciting observations were made throughout this venture and several of the statements made in our references were disproved with our findings. Many reported pearlfish as entering tail first, but we found headfirst entry prominent among our many specimens Myers Homei was reported as living independently from other species, while out of four cases of hosts containing multiple carapids, we found this species living with E. Boraborensis three of those instances Trott and Trott It was stated in Micronesian Reef Fishes among other places that the pearlfish come out to forage at night, but our observations presented different information Myers No foraging occurred during our tests, but these observations were done in aquaria and could be construed do to stress of the specimens.
Evidence of competition was prominent among our observations. Initially, we expected to observe competition interspecifically, but not intraspecifically. However, 6 during out trials it was discovered that in fact aggression was both interspecific and intraspecific.
Though our experiments had a more elevated competitive environment than what was seen in the wild and this provided accurate tests to show that competition was in fact present both interspecifically and intraspecifically. During our trials, tail biting was the most common form of aggression seen, as were few instances of cannibalism. Before our trials began we expected to find to host fidelity among the carapids and their hosts.
However, after twelve trials we found that host preference was in fact not significant and most of the carapids chose to reside in the cucumber that was nearest them. We also expected that a carapid would be able to locate its original host during the trials, but that was not found to be true. Initially we believed that association cues were present for the entry of the Carapid into its Holothurian host. After numerous observations, it was determined that this was true.
The Carapidae was observed to perform several knocking and pecking motions at the cloaca of the Holothurian in order to communicate its entry.
During our assessment of distributions we found a significant difference between location sites of the two carapidae host species with B. There were two cases at PB in which both species were found in one host as well as one instance at WHW. Looking at the pattern of age distributions among fish specimens collected, a two- way ANOVA test revealed a p-value of 0. A large population of adult carapids was found at WHW and was prevalent to the population of juveniles.
Color morphology of B. For example, it would be interesting to conduct further research on the life history of the Carapidae and more specifically, activity within the Holothurian. During dissections of Holothurian hosts, we found carapidae specimens lodged within the respiratory trees and, in once instance inside the gut. We also observed the Carapid entering the Holothurian headfirst and exiting headfirst.
Using such devices such as a sonogram or a hydrophone would be useful in further investigation of the orientation and observation of the Carapid.
During the housing of our specimens we observed carapidae eating through its host in order to exit its host. This behavior was observed but has not been addressed in any other literature.
In the literature it suggests that due to specialized morphology, E. This Carapidae species has well developed jaws and fang-like teeth. Their small eyes and behavior indicate that they would not need to leave their hosts. In contrast, the C.