Bumblebee - Biology

Biology

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 chamber called the spermatheca. This is where the queen stores sperm from her mating. The queen, depending on need, may allow her egg to be fertilised. Non-fertilised eggs become males, and only fertilised eggs grow into females and queens.

As in all animals, hormones play a significant role in the growth and development of the bumblebee. The hormones that stimulate the development of the ovaries are suppressed in female worker bees, while the queen remains dominant. Salivary glands in the head secrete saliva, which mixes with the nectar and pollen. Saliva is also mixed into the nest materials to soften them. The body fat 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 a long hairy structure that extends from a sheath-like modified maxilla. The primary action of the tongue is lapping, i.e. repeated dipping of the tongue into liquid. During lapping, nectar is drawn up the proboscis by capillary action. When at rest or flying, the proboscis is kept folded under the head. The exoskeleton of the abdomen is divided into plates called dorsal tergites and ventral sternites. Wax is secreted from glands on the sternites.

The brightly coloured pile of the bumblebee 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.

Bumblebees do not have ears; however, they can feel the vibrations of sounds through nearby materials.