Wednesday, March 30, 2011
Tuesday, March 29, 2011
Remora are a group of fish that are members of the family Echineidae; there are eight known species, all belonging to one of four genera: Echineis, Phtheirichthys, Remora, and Remorina . They are usually found in warm, southerly waters. Remora interact with a wide range of marine animals. They are known to attach themselves to fish (particularly sharks and rays) and whales, along with other large marine animals – and even the occasional snorkeler or scuba diver . Remora possess a modified dorsal fin that runs from just above the snout of the fish to the nape of its neck. This fin has several transverse plates; it is used by the remora to attach itself to its host. Some remora cling to the host’s torso, but others are found on or near the host’s gills. The name “remora” is the Latin word for “delay”; they were believed to slow down ships and animals that they clung to because of the weight they add and the drag they produce.
Description of the Relationship:
Unfortunately, very little is known about the origin of remora and the evolution of their unique trait and behavior. While other fish – such as the “cleaner fish” studied earlier in the semester – exist in a relationship that superficially resembles the one between a remora and its host, no other identical examples are known.
Depending on the type of remora and the host, the relationship can be either mutualistic or commensal. Most often the relationship is commensal – the remora attach themselves to a host and travel on it, gaining transport, protection from predators, and food. This relationship is commensal when the remora eats scraps left behind by the host or other debris it is exposed to in the host’s travels, but can become mutualistic if the remora is of a variety that eats dead skin and bacteria from the host’s body . In either case the remora benefits from the relationship, while the host either is unharmed or actively benefits along with the remora; for this reason it is impossible to definitively categorize the remora/host relationship as either mutualistic or commensal.
Whether the relationship is commensal or mutualistic, in nature there is little or no harm to the host. In commensal cases, it has an unexpected passenger that does not seek to harm it and that will, at worst, either slow it down by increasing drag on the host as it swims or perhaps cause some minor gill irritation. In mutualistic cases, the host benefits as the remora cleans its host of dead skin, bacteria, and ectoparasites.
Similarly, the remora always benefits from this relationship in a natural environment. Whether the relationship is commensal or mutualistic it gains food, shelter, and protection. Since the remora can detach itself from its host, and is capable of swimming freely, its well-being is not linked to that of the host . Some scientists hypothesize that remora run the risk of being eaten by their hosts, but to date no evidence has been found supporting this idea.
This relationship has incurred some harm for both the remora and their hosts in cases where they live in a human-populated environment due to an unusual fishing practice of some aboriginal tribes. In some regions where remora are prevalent, fisherman use a live remora tied with a long cord in lieu of a fishing hook and rod – they wait until a game fish is spotted, release the remora, allow it to attach itself to the game fish, and then haul both back in with the rope. In some regions the un fortunate remora is eaten along with the game fish, but in other areas they are honored for their contribution to the tribe’s well-being . Despite the man-made disadvantage, the relationship persists because it provides remora with ready food and the high-speed motion they need to keep their gills functioning .
Remora in Action: http://www.youtube.com/watch?v=9z3pqp12UEg
Friday, March 25, 2011
The relationship between Cordyceps and its hosts is strictly parasitic since the Cordyceps end up killing their host. The host ranges from ants to moths to walking sticks. Cordyceps are endoparasitoids meaning they attack inside their hosts; ending up taking over the host brain and body. This fungus spreads its seeds just like any other plant; however once the pollen infects its host is when it acts differently. The cordyceps, still unknown, but somehow travels through the host body until reaching the brain where it infects and takes over them. Infected ants are known to outcast infected ants and even taken as far away from the colony once known infected. The reason for this is the outcome of these infected hosts. They disorientate their host and forces them to attach to nearby limbs. There the fungus does its work by sprouting the fungus sprout out of the head where they later end with a cluster of capsules. When finished, the capsules burst to release more spores into the air to try to infect other host passing by.
The hosts of the Cordyceps ranges from different arthropods such as the Odonata, Blattaria, Hemiptera, Coleopter, Phasmida, Hymenoptera, and Lepidoptera, each depending on the species of the Cordyceps . Even though the Cordyceps affects so many different insects, they are not considered harmful; they are more of nature’s pesticide for insects which get too numerous
Recently Cordyceps are used in Chinese medicine to help fatigue resistance, improve stress tolerance, enhance immune function and improve general health. The specific species the Chinese use is the cordyceps sinensis species which is also known as the Chinese caterpillar.
The Cordyceps are very similar to species we learned in class such as the Dicrocoelium which infects the ant host into controlling the mind. They then force the ant to crawl up stalks and intentionally get eaten by the next host, live stalk. However instead of forcing the ant to crawl and get eaten, Cordyceps kill the ant and release spores from the body of the host.
Monday, March 21, 2011
Friday, March 18, 2011
The species involved in this relationship are Oxpecker,Buphagus africanus or
Buphagus erythrorhynchus, and the Black Rhinoceros, Diceros bicornis. Oxpeckers are located across most of Africa while the Black Rhinoceros is located in the eastern and southern points of the continent. The Oxpeckers and the Black Rhinoceros usually mate near the ned of the rainy season. Oxpeckers usually nest in holes usually in trees and are lined with grasses and hair plucked from the host, The Oxpeckers can usually have 2-3 eggs per breed. . Rhinos on the other hand have one calf after 15 months of incubation .
Description of Relationship:
The Buphagus africanus or Buphagus erythrorhynchus help the Diceros bicornis by eating ticks and other parasites off the body of the rhino. This helps keep the rhino clean while feeding the bird. This shows a mutualistic relationship. Not only does the rhino receive pest control, it also receives a warning system. When the rhino is in danger the oxpecker will take off or start making loud chirping noises which alert the rhino . The oxpecker's role has resulted in the given Swahili name of "askari wa kifaru"; this translates in English to "the rhino's guard" . The oxpeckers do not feed exclusively on rhinos, but they do feed exclusively on the backs of large mammals such as zebras, wildebeests, buffalos, and even giraffes.
Buphagus africanus or Buphagus erythrorhynchus
Injury- It is believed that the oxpecker keeps wounds open by eat the blood and tissue surrounding the wound. This hurts the rhinoceros and prolongs the healing time .
Thursday, March 17, 2011
Monday, March 14, 2011
There are many species of birds that follow massive assemblies of nomadic army ants that share a commensalistic relationship. The bird species include the White-tailed Ant Thrush (Neocossyphus poensis), Brown-chested Alethe (Alethe poliocephala), and Red-tailed Bristlebill (Bleda syndactyla). There are also several species of army ants including Dorylus wilverthi, Dorylus molestus, Labidus praedator, and Eciton burchelli [1,3]. As the army ants swarm across the forest floor in search of insects and arthropods, the birds follow along behind and eat the flying bugs the army ants stir up that the ant can not eat themselves. The birds benefit from the ants foraging, but the ants have little to no harm done to them. Army ant species have been found worldwide on a variety of terrains, although they are most common in tropical and subtropical regions between 45 degrees south and 45 degrees north . Scientists have observed that where army ants reside, there are species of ant-following birds close behind.
DESCRIPTION OF THE RELATIONSHIP:
There are four main families and types of ant-following birds: walkers (Cuculidae), climbers (Dendrocolaptidae), clingers and hoppers (Formicariidae), and perchers (Thraupidae).The largest group of regular ant followers is in the family Formicariidae, but there are more than 50 species that follow ants regularly . These birds species include White-tailed Ant Thrush (Neocossyphus poensis), Brown-chested Alethe (Alethe poliocephala), and Red-tailed Bristlebill (Bleda syndactyla). There are also several species of army ants including Dorylus wilverthi, Dorylus molestus, Labidus praedator, and Eciton burchelli, that are followed by a variety of birds listed above [1,3]. The army ants most likely evolved slowly from individuals to form such massive groups, after recognizing the greater success in predation . Over time, army ants such as E. burchelli and L. praedator have become critical links between bird species and forest floor arthropods, providing food resources that would otherwise be unavailable for many birds in the leaf litter . However, the birds are usually unrelated, and congregate around ant swarms randomly .
WATCH THIS VIDEO!
In this commensalistic relationship, the birds have the greatest benefit of following the army ants, while inflicting little to no harm on the army ants. The birds derive a benefit from the ants by eating the insects and/or arthropods disturbed by the ant “marches” through the forest. There is no break in food availability because ants swarm in almost all seasons and weather.  However, there is some cost for both. Birds do not intentionally try to harm army ants, but occasionally the insects the birds eat that were flushed out by the army ants already have army ants on them. Therefore, the army ants are ingested along with the insects, decreasing the fitness of those ants. A large flock of birds also occasionally takes more insects and/or arthropods than they should in order to not harm the ants’ own diet, which would bend towards parasitism . However, only a small fraction of the total number of birds in a species follows ants, so the amount of food taken from the ants is minimal, bending back towards commensalism . In addition, the ants are somewhat unreliable at high elevations and extreme hot or cold weather . The army ants benefit slightly from the birds eating the excess arthropods because without the birds, the forest floor may become overrun with prey species.
 Willis, Edwin O., and Yoshika Oniki. "Birds and Army Ants." Annual Review of Ecology & Systematics 9 (1978): 243-63. Web.
 Wrege, Peter H., et al. "Antbirds Parasitize Foraging Army Ants." Ecology 86.3 (2005): 555-9. Web.
 Peters, Marcell K., and Benjamin Okalo. "Severe Declines of Ant-Following Birds in African Rainforest Fragments are Facilitated by a Subtle Change in Army Ant Communities." Biological Conservation 142.10 (2009): 2050-8. Web.
 Roberts, Dina L., Robert J. Cooper, and Lisa J. Petit. "Use of Premontane Moist Forest and Shade Coffee Agroecosystems by Army Ants in Western Panama." Conservation Biology 14.1 (2000): 192-9. Web.
 CHAVES-CAMPOS, JOHEL, and J. ANDREW DeWOODY. "The Spatial Distribution of Avian Relatives: Do Obligate Army-Ant-Following Birds Roost and Feed Near Family Members?" Molecular ecology 17.12 (2008): 2963-74. Web.
Sunday, March 13, 2011
Introduction: This blog examines the relationship between the Hawaiian Bobtail Squid and a bioluminescent bacterium. The Hawaiian Bobtail squid acquires an enhanced ability to capture prey and avoid predators, while the bacterium receives key nutrients from residing within the squid . Distribution of this aquatic relationship is limited by the habitat of the squid (Hawaii). Several bioluminescent bacteria cycle through a single squid daily.
Description of Relationship: The type of relationship observed between Euprymna scolope(Hawaiian Bobtail squid) and Vibrio fischeri(bioluminescent bacterium) is unique to organisms with specialized structures called light organs. These light organs are specialized structures that have evolved to allow the organisms that house them to create light. While the evolutionary reason for this structure is unknown, many individuals hypothesize that certain marine organisms form these light organs through adaptation from dark environments in order to increase vision. By using Combes’ logic, this is a textbook example of a symbiosis (when individuals of two species whose evolution has previously been independent associate with one another so that each benefits) . Justification for this statement will be discussed in the cost/benefit analysis section. The life cycle or interaction between these two partners is interesting. Each morning, a squid will eject the bacteria from the previous day and take in new/infant bacteria of that same species. Over the course of the day, the bacteria will multiply and be utilized by the squid at night. The next day the squid repeats this peculiar behavior of ejecting old bacteria and absorbing new bacteria .
Cost/Benefit Analysis: In this relationship, both organisms seem to benefit one another. By properly utilizing the bacteria to reduce its shadow from the moonlight, the Euprymna scolope is able to become a better predator to the prey below and evade its own predators through camouflage. Vibrio fischeri receive a special source of nutrition in the form of amino acids and other essential compounds that are provided to them via the Euprymna scolope’s light organ and bacteria are provided with shelter . The extra weight the squid obtains from housing these bacteria, thus reducing their speed and more likely to be eaten by a predator, is a questionable cost. This cost seems to be outweighed by the beneficial ability the bacteria provide to squid. The squid does not appear to exert any recognizable cost on the bacteria.
 Art of Being a Parasite, Claude Combs
Wednesday, March 2, 2011
Toxoplasmosis is a leading cause of death attributed to food-borne illness in the United States. While a large number of people carry this disease, few actually experience symptoms, as a result of strong immunity. Nonetheless, in the case of the immunodeficient, it can be devastating. Most cases are passed from mother to child; when contracted during pregnancy, the infection can be detrimental and even fatal to the fetus.