|Copyright: Enrico Barbieri (Angel64)
|Date Taken: 2009-06-01|
|Camera: Canon EOS400D|
|Exposure: f/7.1, 1/800 seconds|
|More Photo Info: [view]|
|Photo Version: Original Version|
|Date Submitted: 2009-06-11 0:27|
|[Note Guidelines] Photographer's Note|
|A bumblebee (or bumble bee) is any member of the bee genus Bombus, in the family Apidae. There are over 250 known species, existing primarily in the Northern Hemisphere.|
Bumblebees are social insects that are characterized by black and yellow body hairs, often in bands. However, some species have orange or red on their bodies, or may be entirely black. Another obvious (but not unique) characteristic is the soft nature of the hair (long, branched setae), called pile, that covers their entire body, making them appear and feel fuzzy. They are best distinguished from similarly large, fuzzy bees by the form of the female hind leg, which is modified to form a corbicula; a shiny concave surface that is bare, but surrounded by a fringe of hairs used to transport pollen (in similar bees, the hind leg is completely hairy, and pollen grains are wedged into the hairs for transport).
Like their relatives the honey bees, bumblebees feed on nectar and gather pollen to feed their young.
The blood or hemolymph, as in other arthropods, is carried in an open circulatory system. The body organs, "heart" (dorsal aorta), muscles, etc. are surrounded in a reservoir of blood. The dorsal aorta does pulse blood through its long tube, though, so there is a circulation of sorts.
In fertilised queens the ovaries are activated when the queen lays her egg. It passes along the oviduct to the vagina. In the vagina there is a container called the spermatheca. This is where the queen stores sperm from her mating. Before she lays the egg, she will decide whether to use sperm from the spermatheca to fertilise it or not. Non-fertilised eggs grow into males, and only fertilised eggs grow into females and queens.
As in all animals, hormones play a big role in the growth and development of the bumblebee. The hormones that stimulate the development of the ovaries are suppressed in the other female worker bees while the queen remains dominant. Salivary glands in the head secrete saliva which is mixed with the nectar and pollen. Saliva is also mixed into the nest materials to soften them. The fat body is a nutritional store; before hibernation, queens eat as much as they can to enlarge their fat body, and the fat in the cells is used up during hibernation.
Like all bee tongues, the bumblebee tongue (the proboscis) is composed of many different mouthparts acting as a unit, specialised to suck up nectar via capillary action. When at rest or flying, the proboscis is kept folded under the head. The abdomen is covered with dorsal tergites and ventral sternites. Wax is secreted from glands on the sternites.
The brightly-coloured pile of the bumble bee is a form of aposematic signal. Depending on the species and morph, these colours can range from entirely black, to bright yellow, red, orange, white, and pink. Thick pile can also act as insulation to keep the bee warm in cold weather. Further, when flying a bee builds up an electrostatic charge, and as flowers are usually well grounded, pollen is attracted to the bee's pile when it lands. When a pollen covered bee enters a flower, the charged pollen is preferentially attracted to the stigma because it is better grounded than the other parts of the flower.
A bumblebee does not have ears, and it is not known whether or how a bumblebee could hear sound waves passing through the air, however they can feel the vibrations of sounds through wood and other materials.
Bumblebees are typically found in higher latitudes and/or high altitudes, though exceptions exist (there are a few lowland tropical species). A few species (Bombus polaris and B. alpinus) range into very cold climates where other bees might not be found; B. polaris can be found in northern Ellesmere Island - the northernmost occurrence of any eusocial insect - along with its parasite, B. hyperboreus. One reason for this is that bumblebees can regulate their body temperature, via solar radiation, internal mechanisms of "shivering" and radiative cooling from the abdomen (called heterothermy). Other bees have similar physiology, but it has been best studied in bumblebees.
Bumblebees form colonies. These colonies are usually much less extensive than those of honey bees. This is due to a number of factors including: the small physical size of the nest cavity, a single female is responsible for the initial construction and reproduction that happens within the nest, and the restriction of the colony to a single season (in most species). Often, mature bumblebee nests will hold fewer than 50 individuals. Bumble bee nests may be found within tunnels in the ground made by other animals, or in tussock grass. Bumblebees sometimes construct a wax canopy ("involucrum") over the top of their nest for protection and insulation. Bumblebees do not often preserve their nests through the winter, though some tropical species live in their nests for several years (and their colonies can grow quite large, depending on the size of the nest cavity). In temperate species, the last generation of summer includes a number of queens who overwinter separately in protected spots. The queens can live up to one year, possibly longer in tropical species.
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