Mutualistic Relationships
A mutualistic relationship is when two organisms of different species "work together,"
each benefiting from the relationship. One example of a mutualistic relationship is
that of the oxpecker (a kind of bird) and the rhinoceros or zebra. Oxpeckers land on
rhinos or zebras and eat ticks and other parasites that live on their skin. The oxpeckers
get food and the beasts get pest control. Also, when there is danger, the oxpeckers fly
upward and scream a warning, which helps the symbiont (a name for the other partner
in a relationship).
Organisms in a mutualistic relationship evolved together. Each was part of the other's
environment, so as they adapted to their environment, they "made use of" each other
in a way that benefited both.
Here are three other examples of mutualistic relationships:
1. The bee and the flower. Bees fly from flower to flower gathering nectar, which they
make into food, benefiting the bees. When they land in a flower, the bees get some
pollen on their hairy bodies, and when they land in the next flower, some of the pollen
from the first one rubs off, pollinating* the plant. This benefits the plants. In this
mutualistic relationship, the bees get to eat, and the flowering plants get to reproduce.
2. The spider crab and the algae. Spider crabs live in shallow areas of the ocean floor,
and greenish-brown algae lives on the crabs' backs, making the crabs blend in with
their environment, and unnoticeable to predators. The algae gets a good place to live,
and the crab gets camouflage.**
3. The bacteria and the human. A certain kind of bacteria lives in the intestines of
humans and many other animals. The human cannot digest all of the food that it eats.
The bacteria eat the food that the human cannot digest and partially digest it, allowing
the human to finish the job. The bacteria benefit by getting food, and the human
benefits by being able to digest the food it eats.
*Pollination is when the pollen from one flower gets into another flower, allowing the
plants to reproduce.
** When one of the symbionts lives on or in the other, the one that is lived on or in is
sometimes called the host. However, this term is usually used to describe parasitic
relationships, rather than mutualistic ones.
7 Symbiotic Wonders of
the Seven Seas
by Ecoist
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Evolution alone is an amazing thing – but species that evolve together can be all
the more spectacular, protecting, feeding and cleaning one another in incredible
ways. Sharks pair with fish, fish with shrimp and shrimp with sea cucumbers and
much much more. From boxing crabs that wield poisonous anemones as
weapons to shrimp that scour the mouths of electric eels, here are seven of the
most radical symbiotic relationships from the shallowest to the deepest waters of
our world.
(Images via: Nat.Geographic, AboutFish, DiveGallery, UWPhotos and ScienceBlogs)
The cleaner shrimp seems foolhardy, climbing into the open mouths of sharpfanged eels to dig around for food. These photos seem to depict daring shrimp
shortly before their demise, but actually show an ancient tradition of cleaning.
Moreover, these shrimp have evolved beyond merely finding eels and fish in order
to eat their mouth parasites: they congregate at ‘cleaning stations’ in vast
numbers. And yes, if you are looking for an alternative dental hygienist, they will
even clean your mouth.
(Images via: Flickr, AZAquaCulture, AquariaWorld, DeeperBlue and Diver)
Boxing, hermit and other crabs have found that they make friends with strange
benefits in various species of stinging sea anemones. Boxing crabs (above, top)
hold on to anemones and wield them like deadly pom-poms, warding off potential
predators with their poisonous pals. Some hermit crabs (above, bottom) lift
anemones and attach them to their shells in order to dissuade attackers. These
relationships go both ways: the anemones are able to pick up more food as they
move through the water with their shelled allies.
(Images via: OutbackPhoto, UWPhoto, GuamShellClub and NyTimes)
A happy-looking spotted fish living with a hard-nosed shelled shrimp: it sounds
like something from made-for-kids animated movie. However, the goby and their
shrimp buddies are truly contented cohabitants. They occupy holes together dug
by the shrimp and protected by the goby. The relatively blind shrimp rely on their
strong-sighted goby door guards to signal them about when it is safe to move.
The gobies, in turn, rely on the burrowing shrimp to have a safe place to hide and
sleep.
(Images via: Wikipedia, GreenWater, Infiltec, DaveJenkins and MMcFCuba)
Sharks seem like the most unlikely allies of the ocean: huge, speedy, vicious and
ruthless predators – so why are they so tolerant of remora fish using strange
stickers on their heads to attach to attach to the shark’s underbelly. This was
initially thought to be a case of commensalism – a relationship in which one
species benefits and the other gains nothing – but it is now widely thought that the
remora not only picks up the scraps after a shark has a meal but also cleans the
parasites from its underside.
(Images via: Wikipedia, EarthGuide, OceanExplorer and Nat.Geographic)
The anglerfish is one of the most infamously ugly and unbelievable deep-sea
swimmer, luring unsuspecting victims into is gaping toothed mouth. How does it
accomplish this feat? With the promise of a small glowing prey that is, in fact,
millions of glowing bacteria attached to a fishing-pole-like protrusion from its
forehead. Disturbing side note: to mate, a male angler bites a female slowly dies
and shrivels to a pair of gonads and is carried around by the female until she is
ready to mate with his remains.
(Images via: Sulawesi, Diver, EcoDivers and PhotoNet)
Wait, yet another shrimp? The appropriately named emperor shrimp, however, is
one that benefits more than its partners from its relationships with them. While it is
not a parasite, its rides gain no real advantage from having a shrimp cruising
around on their backs. These hitchhikers of the sea can be found on top of much
larger and faster-moving creatures including nudibranchs and sea cucumbers.
They hang off the sites and pick up scraps from the dirt as their mounts move
about the sea floor.
(Images via: PhotoEnvisions, Wikipedia and Flickr)
The clownfish is virtually the only species of fish that seems able to resist the toxic
effects of sea anemone poison, moving through them unharmed. The anemones
protect them and they eat the leftovers from fish on the anemone including
copepods, isopods and zooplankton. They also fiercely protect their territory,
keeping individual anemones to themselves in small gender-switching selfsufficient groups. Remember Finding Nemo? In real life, Marlin would have turned
female after Nemo’s mother died.