Preferred number (E12 series).Cross section of a Malleefowl (Leipoa ocellata) mound, showing layer of sand (up to 1 m thick) used for insulation; egg chamber; and layer of rotting compost. The egg chamber is kept at a constant 33°C by opening and closing air vents in the insulation layer, while heat comes from the compost below.A trail of wake vorticies generated by a hummingbird's flight. Discovered after training a bird to fly through a cloud of neutrally buoyant helium-filled soap bubbles and recording airflows in the wake with stereo photography.Biological classification.Evolution of seagrasses from algae.Holdridge Life Zone Classification scheme (see larger image map)Blue whale population graph.Why the polar regions are colder: sun's rays there travel through more atmosphere and hit more obliquely, so they're more spread out.Maximum size comparison for tuna species.
Holdridge Life Zone Classification scheme (see larger image map)
