A remora sometimes called a suckerfish or sharksucker, is an elongated, brown

Дата канвертавання22.04.2016
Памер339.75 Kb.
1   2   3   4   5   6   7   8   9

Sea Anemones

  • Sea anemones often stay in one place in the ocean and attach themselves to a surface using a basal disc. Sea anemones are generally between 5 cm and 17 cm long, are very colorful and have the appearance of ocean flowers. The diet of sea anemones consists of shrimp, plankton, fish, isopods and amphipods. Sea anemones are related to jellyfish and corals.

Hermit Crabs

  • Hermit crabs protect their bodies with empty seashells. Hermit crabs move to larger shells to accommodate their bodies as they grow larger. Hermit crabs can range in size from 2 cm to 100 cm. Hermit crabs are usually found in groups and usually live in colonies of 100 crabs or more. The diet of hermit crabs consists of what they scavenge from the ocean floor.


  • Both hermit crabs and sea anemones are ocean creatures, but the creatures have different biological classifications. Hermit crabs are members of the Crustacea subphylum and the Malacostraca class; sea anemones are part of the Cnidaria phylum and the Anthozoa class. Hermit crabs live inside and move between shells; sea anemones use an adhesive "foot" to attach themselves to surfaces on the ocean floor, as well as to hermit crabs.


  • Since sea anemones sometimes attach themselves to the shell of hermit crabs, sea anemones can then eat the food particles that are left floating when a hermit crab eats. Hermit crabs can benefit from the sea anemones that attach themselves to the shell of hermit crabs and can sting predators that put the hermit crabs in danger.

One of the best known examples of symbiosis is that between the hermit crab and a sea anemone (e.g. , Adamsia). The anemone is often found attached to the shell in which the hermit crab lives. In their long history hermit crabs have developed the habit of sheltering within the empty shells of mollusks such as periwinkles and whelks. The hind portion of the has lost its hard covering and would otherwise be unprotected. As the crab gets bigger it outgrows its shelter and so has to find a new one. Often, a sea anemone attaches itself to the crab’s shelter and it may envelop part of the crab’s own shell as well. The growth of the crab and anemone keep pace with each other and the crab has no need to change its shell – more and more of its is sheltered by the anemone. As the crab moves about in search of food the anemone is brought into contact with a greater supply of food and the crab is protected by the anemone’s stinging cells.

Langur Monkey and Chital Deer

The relationship between a troop of hanuman langur monkeys (Presbytis entellus) and chital deer (Axis axis) was examined in Kanha Tiger Reserve, Central Indian Highlands. The frequency distribution of closest approaches between the two species suggested that associations (defined as proximity < 25 m) were not chance encounters; 70.1% of all those herds observed within 200 m came within 25 m of the troop. Associations were more frequent and lasted longer during the hot and cold weather than in the monsoon. Chital initiated and terminated the majority of associations, whilst langurs terminated them more frequently than they initiated. The langur troop dropped a mean of 4.0 kg vegetation fresh weight/day and chital were seen to scavenge or glean this forage in 38.2% of associations; more frequently in the hot and cold weather than in the monsoon. Chital gleaned items from 19 species of tree, with Shorea robusta the most frequently utilized.Responses to potential predators suggested that chital and langur responded to each other's alarm behaviour. Chital alerted to langur alarm more frequently than vice versa. Antagonistic interactions between the two species were observed in 5.8% of associations, predominantly directed from langurs to chital. The study suggests that chital-langur associations are asymmetrical mutualisms. Chital gained by opportunistically taking advantage of vegetation dropped by langurs, and by responding to langur alarm behaviour. The benefit, if any, to langurs was probably slight; they may have gained from responding to chital alarms but incurred costs of antagonism and feeding competition with chital.

1. The Hanuman Monkey – The Gray Langur’s traditional name in India is the Hanuman Monkey. This is because the Gray Langur monkey is mostly grey in color, except for both its black hands and black face. This relates back to Hanuman, a famous monkey god who fought to save the wife of the legendary Indian King Rama. The Langur monkeys came to Hanuman’s aid when he became trapped in a fire and in the process burnt their hands and faces. For this reason, the Gray Langur is sacred in Hindu religion and is not hunted in India.

2. Seven Subspecies: The Gray Langur monkey is the most common monkey found in South Asia with approximately 300,000 existing today. The seven subspecies of this monkey are the Nepal, Kashmir, Tarai, Northern Plains, Black-footed, Southern Plains and the Tufted Gray Langur.

3. They Self-Medicate: The Gray Langur monkey eats a diet that depends highly on what is currently in season and abundant. It maintains a steady diet of fruit, flowers and leaves, preferring mature leaves over young leaves. Insects and everygreen leaves are eaten when others foods are less abundant and bark is only eaten when there is no other food available. The Gray Langur’s diet is high in strychnine, which can be harmful to animals. Therefor it will commonly ingest the gum of the Sterculia Urens to counteract the effects. This gum is marketed in England as a prescription laxative known as Normacol.

4. They Sleep in Trees: Although the Gray Langur spends more time than any other monkey species on the ground, it will sleep in trees at night to avoid predators.

5. Leadership is Short-Term: Gray Langur monkeys live in groups consisting of 11 to 60 monkeys. The group is dominated by a high-ranking male, who usually lasts in the leadership position for an average of 18 months. Often, adolescent males are expelled from the group at an early age and go on to form bachelor groups. These groups will then attack an existing leader in order to overtake his group. All of the children of the dominated leader will then be killed.  

6. Only the Powerful Can Mate: In each group, only the male monkeys that have high-rankings are allowed to mate with any female in the group. The males with lower rankings must sneak their way past a high-ranking male in order to get a chance at copulation with a female. Tough!

7. A Chital Deer’s Best Friend: The Northern Plain Gray Langur monkey's superior eyesight and ability to sit atop high trees allows it to spot predators easily. Researchers have noted that this species will often sit next to herds of the Chital Deer and notify them when a predator is approaching. Additionally, the Langur will often drop fruit from tall trees, which the Chital Deer will then feed on. In return, the Chital Deer’s excellent sense of smell allows it to detect predators early on and warn the Langur that something may be approaching.

Sea Slug and Algae

Elysia chlorotica, common name the eastern emerald elysia, is a small-to-medium-sized species of green sea slug, a marine opisthobranch gastropod mollusc. This sea slug superficially resembles a nudibranch, yet it does not belong to that clade of gastropods. Instead it is a member of the clade Sacoglossa, the sap-sucking sea slugs. Some members of this group use chloroplasts from the algae they eat; a phenomenon known as kleptoplasty. Elysia chlorotica is one of the "solar-powered sea slugs", utilizing solar energy via chloroplasts from its algal food. It lives in a subcellular endosymbiotic relationship with chloroplasts of the marine heterokont alga Vaucheria litorea.

Elysia chlorotica can be found along the east coast of the United States, including the states of Massachusetts, Connecticut, New York, New Jersey, Maryland, Florida (east Florida and west Florida) and Texas. They can also be found as far north as Nova Scotia, Canada.[1]

This species is most commonly found in salt marshes, tidal marshes, pools and shallow creeks, at depths of 0 m to 0.5 m.[1]

Adult Elysia chlorotica are usually bright green in colour, due to the presence of Vaucheria litorea chloroplasts in the cells of the slugs digestive diverticula. However, they can occasionally appear reddish or greyish in colour, thought to depend on the amount of chlorophyll in the branches of the digestive gland which ramify throughout the body.[2] This species can also have very small red or white spots scattered over the body.[2] A juvenile, prior to feeding, is brown with red pigment spots due to the absence of chloroplasts.[3] Elysia chlorotica have a typical elysiid shape with large lateral parapodia which can fold over to enclose the body. Elysia chlorotica can grow up to 60mm in length but are more commonly found between 20mm to 30mm in length.[3]

Elysia chlorotica feeds on the intertidal algae Vaucheria litorea by puncturing the algal cell wall with its radula. The slug then holds the algal strand firmly in its mouth and, as though it were a straw, sucks out the contents.[3] Instead of digesting the entire cell contents, or passing the contents through its gut unscathed, it retains only the algal chloroplasts, by storing them within its own cells throughout its extensive digestive system. The acquisition of chloroplasts begins immediately following metamorphosis from the veliger stage when the juvenile sea slugs begin to feed on the Vaucheria litorea cells.[4] Juvenile slugs are brown with red pigment spots until they feed upon the algae, at which point they become green. This is caused by the distribution of the chloroplasts throughout the extensively branched gut.[3] Initially, the slug needs to continually feed upon algae to retain the chloroplasts, but over time the chloroplasts become more stably incorporated into the cells of the gut enabling the slug to remain green without further feeding.

The incorporation of chloroplasts within the cells of Elysia chlorotica allow the slug to capture energy directly from light, as most plants do, through the process known as photosynthesis. This is significantly beneficial for Elysia chlorotica because during time periods where algae is not readily available as a food supply, the Elysia chlorotica can survive for months on the sugars produced through photosynthesis performed by their own chloroplasts. Kept within the slug's own cells, it has been found that the chloroplasts can survive and function for up to nine or even 10 months.[5] In one study Elysia chlorotica were deprived of alga ingestion for a period of eight months. After the eight-month period, despite the fact that the Elysia chlorotica were less green and more yellowish in colour, the majority of the chloroplasts within the slugs appeared to have remained intact while also maintaining their fine structure.[4] Although Elysia chlorotica are unable to synthesize their own chloroplasts, the ability to maintain the chloroplasts acquired from Vaucheria litorea in a functional state indicates that Elysia chlorotica must possess photosynthesis-supporting genes within its own nuclear genome; most likely acquired through horizontal gene transfer.[5] Since chloroplast DNA alone encodes for just 10% of the proteins required for proper photosynthesis, scientists investigated the Elysia chlorotica genome for potential genes that could support chloroplast survival and photosynthesis. The researchers found a vital algal gene, psbO (a nuclear gene encoding for a manganese-stabilizing protein within the photosystem II complex[5]) in the sea slug's DNA, identical to the algal version. They concluded that the gene was likely to have been acquired through horizontal gene transfer, as it was already present in the eggs and sex cells of Elysia chlorotica.[6]

Fig Tree and Amazon Bat

Fig trees and Amazon fruit bats provide an excellent example of a dependent relationship in nature, a term known as symbiosis. Without each other the fig tree and fruit bat would have a difficult time surviving.

1   2   3   4   5   6   7   8   9

База данных защищена авторским правом ©shkola.of.by 2016
звярнуцца да адміністрацыі

    Галоўная старонка