Juergen Freund / Blue starfish {Linckia laevigata} close up of arm with parasitic snails {Thyca crystallina} attached, Indo-Pacific

Doug Perrine / Parasitic sea snail {Thyca crystallina} camouflaged on arm of blue sea star {Linckia laevigata} Mabul Island, Sabah, Borneo, Malaysia

Fred Bavendam / Limpet (Thyca crystallina) living on coral surface and the Blue Sea Star (Linckia laevigata), Manado, North Sulawesi, Indonesia

Jack Dykinga / Autumnal Bigtooth Maples (Acer saccharum grandidentatum), West Fork Oak Creek, Coconino National Forest, Arizona

Jack Dykinga / Red and Yellow coloured Bigtooth Maples (Acer saccharum grandidentatum) in Autumn, West Fork Oak Creek, Coconino National Forest, Arizona

Jack Dykinga / West Fork Oak Creek at base of Supai sandstone cliffs, mixed forest of oak, maple and conifers in background, Coconino National Forest, Arizona

Jim Brandenburg / Oak (Quercus sp) leaves in stream with snowy forest, Minnesota

Tim Fitzharris / Oak Creek in Slide Rock State Park near Sedona, Arizona

Tim Fitzharris / Oak Creek in Slide Rock State Park near Sedona, Arizona

Tim Fitzharris / Oak Creek in Slide Rock State Park near Sedona, Arizona

Tim Fitzharris / Oak Creek in Slide Rock State Park near Sedona, Arizona

Tim Fitzharris / Oak Creek at Grasshopper Point, Sedona, Arizona

Jack Dykinga / Cathedral Rock reflected in water at Oak Creek Crossing, Coconino National Forest, Arizona

Jack Dykinga / West Fork Oak Creek with flowering Cardinal Flower (Lobelia cardinalis) Coconino National Forest, Arizona

Jack Dykinga / Golden Columbines (Aquilegia chrysanta) flowering on bank of West Fork Oak Creek at the base of Supai sandstone cliffs, Coconino National Forest, Arizona

Jack Dykinga / Golden Columbines (Aquilegia chrysanta) flowering on bank of West Fork Oak Creek at the base of Supai sandstone cliffs, Coconino National Forest, Arizona

Jack Dykinga / Cathedral Rock reflected in water at Oak Creek Crossing, Coconino National Forest, Arizona

Tim Fitzharris / Cathedral Rock reflected in Oak Creek at Red Rock Crossing, Red Rock State Park near Sedona, Arizona

Tim Fitzharris / Cathedral Rock reflected in Oak Creek at Red Rock Crossing, Red Rock State Park near Sedona, Arizona

Jack Dykinga / Juniper {Juniperus monosperma} studded grasslands with Sycamore and Oak Creek Canyons in background, Prescott National Forest, Arizona, USA

David Welling / Oak creek running before Cathedral Rocks, Red Rock Crossing, Sedona, Arizona, USA

Larry Michael / Oak tree (Quercus sp) beside creek in autumn, Wisconsin, USA, sequence 5 / 6

Larry Michael / Oak tree (Quercus sp) beside creek in summer, Wisconsin, USA, sequence 4 / 6

Larry Michael / Oak tree (Quercus sp) beside creek in late spring, Wisconsin, USA, sequence 3 / 6

Larry Michael / Snow covered Oak tree (Quercus sp) beside creek in deep winter, Wisconsin, USA, sequence 1 / 6

David Welling / Cathedral Rocks from Oak Creek, Red Rock Crossing, Sedona, Arizona, USA

Larry Michael / Oak tree (Quercus sp) beside creek in late spring, Wisconsin, USA, sequence 2 / 6

Larry Michael / Snow covered Oak tree (Quercus sp) beside creek in early winter, Wisconsin, USA, sequence 6 / 6

Tim Fitzharris / Cathedral Rock reflected in Oak Creek at Red Rock crossing with gathering rain clouds, Red Rock State Park near Sedona, Arizona

Tim Fitzharris / Cathedral Rock reflected in Oak Creek at Red Rock crossing, Red Rock State Park near Sedona, Arizona

Tim Fitzharris / Oak (Quercus sp) trees covered with moss at Eagle Creek, springtime, Columbia River Gorge, Oregon