Commensal and Parasitic Barnacles - Term Paper Example

Commensal and Parasitic Barnacles Barnacles are arthropods belonging to Cirripedia under subphylum Crustacea. It is therefore related to crabs and other forms of sea crustaceans. The only difference between barnacles and the other arthropods is that the former have sessile species, or species that cannot move from one place to another. Barnacles are both commensals and parasites. As commensals, barnacles usually benefit from their hosts by having a place to stay, and being carried to nutrient-rich areas of the sea (“Hitchhiker”). Although the host animal, such as whales, does not benefit from barnacles attached to its body, the host remains unaffected. On the other hand, parasitic barnacles bore through the exoskeleton of the host and moves to the blood and the midgut of the animal until it branches into a mass of harmful tissue, thus killing the animal host (“Sacculina”). Overall, there are several types of barnacles but only four orders. Order Thoracica or the “True Barnacles” The first order of barnacles is the order Thoracica, or the “true barnacles” Newman & Abbott). The Thoracica are the most important because they are more abundant and more conspicuous than the species of the other orders. Although the Thoracica occur most abundantly in the tropical Indo-Pacific region of the ocean, they are basically found in all types of marine environments, both in saltwater and freshwater. However, it remains a fact that “none completes its life cycle in freshwater” (Newman & Abbott). The average size of a Thoracica barnacle is “generally moderate, a few centimeters in greatest dimension, but some…exceed 10 cm and others but a few millimeters” (Newman & Abbott). The adult Thoracica is basically “permanently attached” yet most do not shed off their calcareous shell all throughout their lives (Newman & Abbott). It is actually the Thoracica barnacles that form symbiotic relationships with organisms that are much larger than the average size of the true barnacles: “whales, sea snakes, lobsters, medusa, corals and sponges” (Newman & Abbott). With the aforementioned animals, the true barnacles acted as commensals. However, a few true barnacles have actually become “nutritionally dependent” on larger animals like shark, corals or worms, especially during the earlier stages of barnacle evolution, and although their symbiosis was only for “support or protection,” these relationships were still considered parasitic (Newman & Abbott). There are three suborders of Thoracica barnacles: the stalked barnacles or Lepadomorpha, the assymetrical sessile barnacles or the Verrucomorpha, and the symmetrical sessile barnacles or the Balanomorpha. The Lepadomorpha or stalked barnacles usually have a body “divided into a capitulum with cirri and mouthparts as feeding appendages, and a peduncle or stalk which attaches the animal to the substratum. Occasionally, the capitulum and the peduncle are heavily laden with calcareous plates (Newman & Abbott). Source: http://cccmkc.edu.hk/~kei-kph/Ecology/Stalked%20barnacle_Pollicepes.htm Certain Lepadomorpha barnacles, which act as commensals, are usually found in the teeth of the pygmy killer whale or Feresa attenuata, the sperm whale or Physeter macrocephalus, the goosebeak whale or Ziphius cavirostris, and the Antillean beaked whale or Mesoplodon europaeus, as well as other cetaceans that thrive the deep marine waters (Mignucci-Giannoni, “Metazoan Parasites”). One unique Lepadomorpha barnacle is the goose barnacle or Lepas anserifa, which is similar to the Balanomorpha or acorn barnacles because of its protective shell (“Barnacles”). The buoy barnacle, or Dosima fascicularis, is also closely related to the goose barnacle. Although almost all true barnacles are commensals, based on early research, there is a Lepadomorpha barnacle which is parasitic and that is the Conchoderma virgatum (Williams; Hastings). According to information from Williams, the Conchoderma can parasitize two species of whale and nine species of bony fishes (Williams). Other species infested by the Conchoderma, include “crabs, sea snakes, turtles, whales, and sea weed” (Hastings). Moreover, it was also found out that the Conchoderma may subsist on copepods or free-floating freshwater crustaceans as well as elasmobranches or cartilaginous fish (Williams). One particular cartilaginous fish that the Conchoderma barnacle is ready to parasitize is the Galeocerdo cuvieri or the tiger shark (Williams). The Verrucomorpha or the assymetrical sessile barnacles do not have the peduncle, which means that the capitulum is directly in contact with the substratum. This contact therefore forms a rigid wall and in other species there is the formation of the operculum or movable lid. The presence of the operculum somehow makes the Verrucomorpha and other sessile barnacles to be better adapted to many different kinds of habitats. However, the Verrucomorpha, in particular, is mostly found in deep water (Newman & Abbott). Just like the Verrucomorpha barnacles, the Balanomorpha or symmetrically sessile barnacles, or acorn barnacles, they also do not have the peduncle but have a rigid wall and an operculum. However, while the Verrucomorpha barnacles thrive in the deep water, the Balanomorpha are most abundant on the shore (Newman & Abbott). Source: http://score.dnr.sc.gov/species/barnacles.htm The Balanomorpha or acorn barnacles are also known to withstand severe weather as well as climatic changes like the extreme heat of summer and the freezing cold of winter. Moreover, the acorn barnacles are “cemented to the rock” and therefore cannot move even when threatened by severe weather conditions, thus resulting in their dessication, or total drying out or loss of moisture (“Barnacles,” Pznow). Moreover, certain Balanomorpha barnacles, like the Coronula species and Conchoderma auritum, were found attached to the skin of humpback whales or Megaptera novaeangliae. Nevertheless, the Coronula species of barnacles are most numerous in the North Atlantic, where the North Atlantic right whale, or Eubalaena glacialis, thrives (Mignucci-Giannoni et al., “Metazoan Parasites”). Other Balanomorpha barnacle species, the Platylepas hexastylos and the Chelonibia testudinaria, are known to act as commensals frequently associated with loggerhead turtles and green turtles in general (Bugoni et al.). Generally, the true barnacles – the Lepadomorpha, Verrucomorpha, and Balanomorpha – are commensals, although occasionally, as previously mentioned, some are parasitic. Order Ascothoracica While the true barnacles are commensals, the Ascothoracica are the barnacles that are considered “semi-predaceous carnivores [as well as] obligate parasites on various corals and echinoderms” (Newman & Abbott). Perhaps what makes the Ascothoracica barnacles unique from the rest of the species is that it has a bivalve shell, and that they use their thoracic limbs for swimming instead of obtaining food, and the inability to attach permanently (Newman & Abbott). Order Acrothoracica The Acrothoracica barnacles are distinguishable from the other species because they are “generally very small” (Newman & Abbott). Another distinct characteristic of this particular order of barnacles is that they have limbs that are located at the end of the thorax (Newman & Abbott). Order Rhizocephala The Rhizocephala barnacles are parasites which are “highly modified” and primarily depend on decapods crustaceans, such as shrimp, crabs, lobsters, crayfish and prawns (Newman & Abbott). The Rhizocephala barnacle attaches itself to the host as a cyprid larva and it metamorphoses into a kentrogon, and as it keeps growing, it sends out roots into the body of the crustacean host (Pawlik). Based on the research conducted by Joseph R. Pawlik in the Journal of Crustacean Biology, among the various species of Rhizocephala barnacles, which are parasitic, include Chthamalophilus delagei, Boschmaella balani, Balanus improvisus, Bocquetia rosea, and Membranobalanus orcutti (Pawlik). Another parasitic Rhizocephala barnacle, Chelonibia manati, which was discovered in 1916, is known to infest most West Indian manatees of Puerto Rico and the Caribbean (Mignucci-Giannoni et al., “Parasites and Commensals”). Another Rhizocephala barnacle is the Sacculina carcini barnacle, which is very popular as a parasite. This is unlike most other barnacles which are previously described because it has “no hard body parts” or that its flesh is exposed freely (“Barnacles,” PzNow). The Sacculina parasitizes mostly female crabs, where the Sacullina produces a reproductive mass in a sponge-like appearance and resembling the egg of the crab (“Barnacles,” PzNow). Once this reproductive mass attaches to the egg of the crab, the crab does not realize it and therefore takes care of and nourishes the egg of the Sacculina. Perhaps, one striking quality of the Sacculina barnacle is that it interferes with the molting process that the crab must regularly undergo (“Barnacles,” PzNow). The parasitized crab therefore does not undergo molting. Predators of Barnacles It is, however, interesting to note that barnacles are eaten by “worms, snails, sea stars, sheephead fish, and some shorebirds” (“Barnacles,” Oracle ThinkQuest). However, oil spills and extremely high temperatures can also dessicate barnacles (“Barnacles,” Oracle ThinkQuest). A Barnacle that Causes Sex Change in Its Host Perhaps, the most interesting barnacle is the parasitic Sacculina carcini, which is a Rhizocephala barnacle. It is interesting because early research indicated that most male crabs parasitized by the Sacculina barnacle transform into females because the barnacle destroys the androgenic gland of the male crabs. The male crabs then transform into females. The Sacculina needs the crab to be female because the former needs to deposit its own brood sac on the crab’s body (“Sacculina). Top of Form Bottom of Form Works Cited Barnacles.” 2012. Oracle ThinkQuest. 27 Mar 2012. Barnacles.” 2012. PzNow. 27 Mar 2012. Bugoni L, Krause L, de Almeida AO & de Padua Bueno AA. “Commensal Barnacles of Sea Turtles in Brazil.” Marine Turtle Newsletter 94:7-9 (2001). Sea Turtle Organization G. Mendez. 27 Mar 2012. Hastings RW. “The Barnacle, Conchoderma virgatum (Spengler), in Association with the Isopod, Nerocila acuminata Schioedte & Meinert, and the Orange Filefish, Alutera schoepfi (Walbaum).” Crustaceana 22 (3):274-278 (1972). JSTOR. 25 Mar 2012. Hitchhikers: Free Rides on Gray Whales.” 2012. Journey North. 27 Mar 2012. Mignucci-Giannoni AA, Beck CA, Montoya-Ospina RA & Williams, EH Jr. “Parasites and Commensals of the West Indian Manatee from Puerto Rico.” Journal of the Helminthological Society of Washington 66 (1):67-69 (1999). Sistema Universitario Ana G. Mendez. 26 Mar 2012. Mignucci-Giannoni AA, Hoberg EP, Siegel-Causey D, Williams EH Jr. “Metazoan Parasites and Other Symbionts of Cetaceans in the Caribbean.” The Journal of Parasitology 84 (5):939-946 (1998). Sistema Universitario Ana G. Mendez. 27 Mar 2012. Newman WA & Abbott DP. “Cirripedia: The Barnacles.” 2012. Atol Decapoda. 27 Mar 2012. Pawlik JR. Bocquetta rosea, a New Genus, New Species, an Unusual Rhizocephalan Parasite of a Sponge-Inhabiting Barnacle, Membranobalanus orcutti (Pilsbry) from California. “Parasites and Commensals of the West Indian Manatee from Puerto Rico.” Journal of Crustacean Biology 7 (2):265-273 (1987). University of North Carolina Wilmington. 26 Mar 2012. Sacculina: A Highly Modified Parasite.” n.d. McGraw Hill Higher Education. 27 Mar 2012. Williams EH Jr. “Conchoderma virgatum (Spengler) (Cirrepedia Thoracica) in Association with Dinemoura latifolia (Steenstrup & Lutken) (Copepoda, Caligidea), a Parasite of the Shortfin Mako, Isurus oxyrhynchus Rafinesque (Pisces, Chondrichthyes).” The Journal of Parasitology 84 (5):939-946 (1998). Recinto Universitario de Mayaguez. 27 Mar 2012. Read More