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from article Breadfruit
Breadfruit (Artocarpus altilis), showing the rounded (or elliptic) fruit and the cylindrical staminate flower cluster. (Photo courtesy of Forest and Kim Starr)
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from article Island biogeography
Equilibrium number of species (Sequilibrium) is determined by the intersection of the immigration ( I ) and extinction ( E ) rate curves. P is the maximum number of species in the source pool.
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from article Digenea
Diagrams of various adult types of digenean trematodes. (After R. M. Cable, An Illustrated Laboratory Manual of Parasitology, Burgess, Minneapolis, 1940)
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from article Digenea
Digenean trematode life cycle. (After R. M. Cable, An Illustrated Laboratory Manual of Parasitology, Burgess, Minneapolis, 1940)
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from article Hydroponics
Green- and red-leaf lettuce growing in a hydroponic vegetable garden on a bamboo fence. The pipes, which supply nutrients and water, are part of the hydroponic system. (Credit: Piyachok Thawornmat, Shutterstock)
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from article Hydroponics
Hydroponic techniques: (a) aerated standing culture; (b) flowing-solution culture with standing solution; (c) nutrient film technique; (d) aeroponics.
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from article Mango
Tommy Atkins cultivar of mango (Mangifera indica) growing in Florida. (Credit: Wilhelmina Wasik/Agricultural Research Service, U.S. Department of Agriculture)
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from article Tomato
Tomatoes (Solanum lycopersicum). (Credit: Peggy Greb, Agricultural Research Service, U.S. Department of Agriculture)
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from article Tomato
Tomato affected by anthracnose (caused by the fungus Colletotrichum phomoides). (Credit: U.S. Department of Agriculture Cooperative Extension Slide Series, Clemson University)
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from article Tomato
Tomatoes showing blossom-end rot. (Credit: Mary Ann Hansen, Virginia Polytechnic Institute and State University)
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from article Learning
Lateral view of the human brain, including the primary areas of the frontal, temporal, parietal, and occipital lobes. (Copyright © McGraw-Hill Education)
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from article Learning
Brain activity can be recorded in various ways, from single-cell activity (top tracing) to the familiar electrical patterns ("brain waves") of an electroencephalogram (bottom tracing). (Credit: Based on an original drawing by C. Cotman and J.…
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from article Pine nut
Pine nuts in their hard shell (Mexican piñon pine, Pinus cembroides). (Photo by Steve Hurst, U.S. Department of Agriculture–Natural Resources Conservation Service PLANTS Database)
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from article Pine nut
Cone containing pine nuts (stone pine, Pinus pinea). (Photo by Vito Buono, Bari, Italy)
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from article Biofilm
Biofilms are highly structured communities of microorganisms that are surface-associated or attached to one another, and are enclosed within a self-produced protective extracellular matrix. Biofilm formation and actions involve a number of stages:…
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from article Ctenothrissiformes
A Cretaceous ctenothrissiform fossil, Ctenothrissa sp. (order Ctenothrissiformes), on a limestone matrix found in Lebanon. Size: 90 mm (3.5 in.). (Photo courtesy of The Virtual Fossil Museum)
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from article Acari
Parasitiformes body plan. Lateral view of a predatory adult female Mesostigmata showing major body regions and important structures. Scale bar = 0.1 mm (0.004 in.). (Scanning electron micrograph by D. E. Walter)
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from article Acari
Acariformes body plan. (a) Adult female Oribatida (Sarcoptiformes) in lateral view showing major body regions and important structures. (b) Hexapod larva (Trombidiformes): dorsal view of a chigger, a parasite of vertebrates. (c) Octopod deutonymph…
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from article Ecosystem
Levels of organization in ecosystems, which involve both biotic (living) components and abiotic (nonliving, physical) components. (Copyright © McGraw-Hill Education)
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from article Ecosystem
General model of energy flow through ecosystems. (Copyright © McGraw-Hill Education)
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from article Ecosystem
Food chains are limited by energy transfer. In this illustration, energy is transferred from the Sun to a plant (producer) to a primary consumer and to a secondary consumer. Energy is used by the producer and consumer organisms and is lost to the…
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from article Ecosystem
General model of the nitrogen cycle in ecosystems. (Copyright © McGraw-Hill Education)
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from article Ecosystem
General model of the carbon cycle in ecosystems: (A) carbon dioxide (CO2) from the air; (B) carbon from decomposition; (C) carbon from fossil fuels; (D) natural events (for example, forest fires and volcanoes) release CO2 into the air. (Copyright ©…
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from article Poplar
Quaking aspen (Populus tremuloides). (Photo courtesy of North Dakota State Soil Conservation Committee, USDA–NRCS PLANTS Database)
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from article Poplar
Common poplar species. (a) Quaking aspen (P. tremuloides); leaf scar with an axial bud, leaf, and twig. (b) Bigtooth aspen (P. grandidentata); leaf, terminal bud, and twig. (c) Cottonwood poplar (P. deltoides); leaf, leaf scar, terminal bud, and…
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from article Biodiversity
Global biodiversity hotspots. There are more than 30 biodiversity hotspots located around the world. These areas have experienced severe habitat losses (at least 70%) as the result of human activities, hampering the work of conservationists in their…
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from article Biodiversity
A regional analysis of 25 oceanic regions shows that 92% of all known biodiversity falls into a dozen groups, of which crustaceans (for example, crabs, shrimps, and lobsters), mollusks (for example, snails, bivalves, squids, and octopus), and fish…
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from article Biodiversity
Ecosystem function (a) as a positive, linear function of biodiversity and (b) as a nonlinear, satiating function of biodiversity. (Copyright © McGraw Hill)
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from article Haplosporida
Spore of Urosporidium fuliginosum.
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from article Haplosporida
Stages in the development of Icthyosporidium giganteum.
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from article Urodela
A typical member of the order Urodela: the longtail salamander (Eurycea longicauda). (Credit: Ryan Hagerty/U.S. Fish and Wildlife Service)
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from article Urodela
Southern dwarf siren (Pseudobranchus axanthus), which has undergone limb degeneration and retains only tiny forelimbs. (Credit: U.S. Geological Survey)
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from article Urodela
World distribution of salamanders (order Urodela), indicated by areas of shaded blue color. (Copyright © McGraw Hill)
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from article Urodela
California tiger salamander (Ambystoma californiense). (Credit: John Cleckler/U.S. Fish and Wildlife Service)
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from article Urodela
The two-toed amphiuma salamander (Amphiuma means). (Credit: Southeast Ecological Center, U.S. Geological Survey)
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from article Urodela
The northern red salamander (Pseudotriton ruber ruber) is a member of the family Plethodontidae. (Credit: Alicia Lafever/U.S. National Park Service)
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from article Thirst and sodium appetite
Regulation of cellular water. ADH = antidiuretic hormone.
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from article Thirst and sodium appetite
Hypovolemic thirst and sodium appetite are caused by altered sensory information from an underfilled circulation, reinforced by increases in circulating angiotensin II and mineralocorticoids. Angiotensin peptides generated from components of a…
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from article Chamois
Alpine chamois (Rupicapra rupicapra). (Photograph courtesy of Brent Huffman/Ultimate Ungulate Images)
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from article Environmental management
Environmental management seeks to provide solutions to the practical problems that humans encounter or create, including the production of garbage and waste. (Credit: Walter Zerla/Getty Images)
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from article Environmental management
Without proper environmental management, economic and industrial development often lead to environmental pollution, especially in urban environments. (Credit: Simon Alvinge/123RF)
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from article Chicxulub impact crater
Bouguer gravity anomaly map over the Chicxulub impact crater. The coastline is designated by a thin white line, cenotes (natural pits) and sinkholes are designated by black dots, and the city of Mérida and the town of Chicxulub Puerto are designated…
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from article Chicxulub impact crater
Seismic line imaging of what lies beneath the seafloor, showing the Chicxulub impact crater. The crater includes many faults that can be grouped into an exterior ring fault, a series of outer ring faults, and a series of inner ring faults. Within…
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from article Amniota
Basic types of vertebrate eggs.
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from article Amniota
Embryo developing in amniote eggs.
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from article Osage orange
Fruit and foliage of osage orange (Maclura pomifera). (Photo copyright © Karren Wcisel)
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from article Mecoptera
Male scorpion fly (Panorpa), order Mecoptera.
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from article Marine ecology
Marine ecology investigates the basic structural and functional relationships within and among living populations and their physical–chemical environments in marine ecosystems. In this photograph, a cold water reef in California is host to a…
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from article Marine ecology
The snaking waterways of a mangrove estuary in northwestern Madagascar. (Credit: Michael Fay/Getty Images/National Geographic RF)
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from article Marine ecology
Estuary salt marshes in the Grand Bay National Estuarine Research Reserve, Mississippi. (Credit: P. R. Hoar/National Oceanic and Atmospheric Administration)
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from article Marine ecology
Coral bleaching in the lagoon of Huahine Island, French Polynesia. Coral bleaching is the response of corals to environmental stress in which they eject the single-cell algae that live within the transparent coral tissue, making the white coral…
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from article Graptolithina
Sketches of portions of pterobranch and graptolite colonies showing the dwelling tubes and the constructional units of the graptolite skeleton. (a) Young Rhabdopleura compacta colony with founder zooid and first asexual bud (Recent). Benthic…
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from article Graptolithina
Scanning electron micrograph of a graptolite (Pseudoclimacograptus scharengergi) showing the fuselli (horizontal ridges) that compose graptolite thecae, and the cortical bandages (oblique strips) that were deposited on top of the fuselli (Middle…
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from article Graptolithina
Hypothetical form of zooids that inhabited colony tubes, based on a planktic graptolite. Large zooids are shown with possible oarlike swimming organs used to move the colony through the ocean water and tentacles for feeding. Also shown are two…
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from article Graptolithina
Examples of some planktic graptolites, reconstructed to show three-dimensional form.
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from article Magnolia
Flowers and leaves of the southern magnolia (Magnolia grandiflora). (Photo courtesy of Forest and Kim Starr)
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from article Hackberry
Hackberry (Celtis occidentalis). (Credit: North Dakota State Soil Conservation Committee, USDA–NRCS PLANTS Database)
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from article Swamp, marsh, and bog
Young cypress trees growing out of a swamp located in the Florida Everglades. (Credit: Getty Images)
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from article Hemiptera
Phylogenetic relationships among the extant Hemiptera groups.
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from article Hemiptera
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from article Hemiptera
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from article Hemiptera
Mouthparts and method of feeding of a plant bug.
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from article Hemiptera
Plant pests. (a) A colony of aphids on a rose shoot. (b) The citrus mealybug. (Ohio Agricultural Experiment Station)
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from article Hemiptera
An aphid (dorsal aspect).
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from article Hemiptera
Anterior dorsum of various Auchenorrhyncha: (a) cicada; (b) fulgoroid (apical part of antenna omitted); (c) another species of fulgoroid; (d) cercopid; (e) membracid, anterior view of face and pronotum.
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from article Hemiptera
Membracids on stems: (a) adult; (b) nymphs. (Courtesy of C. H. Hanson)
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from article Hemiptera
Peloridora kuscheli China (Peloridiidae).
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from article Hemiptera
Triatoma pallidipennis (Reduviidae). (Photo by E. S. Ross)
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from article Hemiptera
External anatomy of a typical bug.
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from article Hemiptera
Squash bug. (Photo by Scott Bauer, Agricultural Research Service, U.S. Department of Agriculture)
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from article Hemiptera
Brown marmorated stink bug (Halyomorpha halys): adult (top) and fifth-instar nymph (bottom). (Photo by Stephen Ausmus, Agricultural Research Service, U.S. Department of Agriculture)
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from article Hemiptera
Oblique-dorsal view of a bedbug, Cimex lectularius. (Photo by Piotr Naskrecki, Public Health Image Library)
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from article Hemiptera
Nymph of the tarnished plant bug (Lygus lineolaris). (Photo by Scott Bauer, Agricultural Research Service, U.S. Department of Agriculture)
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from article Chestnut
American chestnut (Castanea dentata). (Photo courtesy of Forest and Kim Starr)
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from article Chestnut
Nuts of the Allegheny chinquapin (Castanea pumila). (Photo courtesy of Steve Hurst, USDA–NRCS PLANTS Database)
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from article Obolellida
Obolella. (a) Shell exterior (after J. Hall and J. M. Clarke, An introduction to the study of the Brachiopoda intended as a handbook for the use of students, Report of the N.Y. State Geologist for 1891, 1894). (b) Dorsal valve interior, and (c)…
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from article Caraway
Caraway (Carum carvi) fruits (often called “seeds”). Scale bar = 1 mm. (Photo by Steve Hurst; USDA–NRCS PLANTS Database)
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from article Air navigation
Typical wind triangle, drawn to scale. 1 knot = 1 nmi/h = 0.514 m/s.
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from article Air navigation
Electronic map display developed by a flight management computer on the pilot's instrument panel of a Boeing 767 airplane. (United Airlines)
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from article Air navigation
Loran C chain GRI 7980 in the southeastern United States, comprising primary station M and secondary stations W, X, Y, and Z. A position fix is shown at point A, where the lines of position 7980-Y-45000 and 7980-Z-61000 intersect.
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from article Enantiornithes
Protopteryx, the most primitive known enantiornithine bird, collected from the Early Cretaceous of Hebei Province, northern China.
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from article Dallis grass
Dallis grass (Paspalum dilatatum). (Photo courtesy of Larry Allain, USGS National Wetlands Research Center)
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from article Albuliformes
Albula vulpes. (Courtesy of C. Q. Jessen)
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from article Carnauba wax
Carnauba wax palm (Copernicia prunifera). The leaves of this palm are the source of carnauba wax. (Photo courtesy of Scott Zona)
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from article Mollusca
Higgins eye pearly mussels (Lampsilis higginsii). (Credit: U.S. Fish and Wildlife Service)
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from article Mollusca
Snails are assigned to the class Gastropoda in the phylum Mollusca. (Credit: Zuzha/Shutterstock)
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from article Mollusca
Generalized model of a stem mollusk (or archetype) in side view. There are three distinct regions in the molluscan body: head-foot, visceral mass, and mantle-shell. Water circulation through the mantle cavity, gills (ctenidia), and pallial complex…
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from article Mollusca
Arrangement of the mantle and shell layers in mollusks. The fleshy mantle margin is divided into three lobes, and the outer pallial lobe is largely responsible for secretion of the three layers of the shell. (Credit: W. D. Russell-Hunter)
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from article Mollusca
Aspidobranch ctenidium (feather or plume gill) as found in primitive gastropods and other molluscan groups. (a) Stereogram showing the water current from the ventral inhalant to the dorsal exhalant between adjacent gill plates; this current is…
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from article Mollusca
Common octopus (Octopus vulgaris). (Credit: Aerial-motion/Shutterstock)
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from article Heterotrichida
Climacostomum, an example of a heterotrich.
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from article Paleoecology
Zonation of Silurian (425 million year old) marine communities in the Welsh Basin, United Kingdom. Marine animal communities were typically arranged in belts parallel to the shoreline and related to water depth. A classic study using fossil…
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from article Paleoecology
Classification of shales in terms of percentages of three benthic habitat groups: epifaunal suspension-feeding bivalves (those living at the sediment-water interface and filtering seawater), infaunal (living within and feeding on the sediment), and…
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from article Paleoecology
Comparison of four developmental stages in four ancient reef masses. (After K. R. Walker and L. P. Alberstadt, Ecological succession as an aspect of structure in fossil communities, Paleobiology, 3:238–257, 1975)
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from article Paleoecology
Formation and burial sequence of Bobcaygeon hardground. (a) Soft-bottom community of strophomenid brachiopods and infaunal burrowers inhabiting carbonate mud. (b) Hardground community consisting of boring and encrusting organisms. (c)…
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from article Paleoecology
Tiering or vertical depth stratification in marine communities through time. Note the rapid rise of the highest-tier (level) organisms (crinoids or sea lilies, bryozoans) from a few centimeters to over a meter above the sea floor during the…
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from article Paleoecology
The three great marine evolutionary faunas of the Phanerozoic. The Cambrian fauna, composed of trilobites, primitive groups of brachiopods, and mollusks, arose early during that period to a diversity of about 50 families, and then dwindled during…
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from article Coral reef structural complexity
A fire coral before and after bleaching, which can occur when coral are environmentally stressed. The fire coral on the left is healthy, whereas the one on the right is completely bleached. (Credit: XL Catlin Seaview Survey)
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from article Coral reef structural complexity
Underwater photographs of Cane Bay (St. Croix, U.S. Virgin Islands) in 1980 (left) and 2007 (right). Note the common overgrowth of fleshy macroalgae between the sparsely distributed corals in 2007 compared to the more open substrate in 1980 between…
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from article Coral reef structural complexity
Historical changes related to coral reef decline since the 1600s. The emergence of temperature-related responses (bleaching and disease) is coincident with the loss of urchins (Diadema) and the increase of nutrient loading.
