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from article Anostraca
Branchinecta paludosa, male, small specimen, lateral aspect.
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Image
from article Salmon farming
Adult Atlantic salmon (Salmo salar). (Credit: William Hartley/U.S. Fish and Wildlife Service)
Image
from article Salmon farming
Atlantic salmon (Salmo salar) at a pre-smolt stage. (Credit: Edward Peter Steenstra/U.S. Fish and Wildlife Service)
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from article Salmon farming
A congregation of coho salmon (Oncorhynchus kisutch) released from a hatchery. Investigators continue to study the effects of farmed fish on neighboring populations of wild salmonids. (Credit: Salmon Ecology Team/Southwest Fisheries Science Center,…
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from article Suctoria
Endogenous budding in the suctorian Podophrya, a species which measures 10–28 μm.
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from article Jawless vertebrate
Interrelationships of jawless and jawed vertebrates, showing the distribution of some major evolutionary steps. (Copyright © McGraw Hill)
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from article Psocoptera
Valenzuela flavidus, male (family Caeciliusidae): habitus (general appearance). Body length: 2.02 mm (0.08 in.).
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from article Psocoptera
Metylophorus novaescotiae, female (family Psocidae): habitus. Body length: 5.24 mm (0.2 in.).
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from article Psocoptera
(a–e) Mouthparts of a typical psocid, Echmepteryx hageni (family Lepidopsocidae): a = labrum, b = maxilla (l = lacinia), c = hypopharynx (li = lingual sclerite), d = mandible, e = labium. Scale: 0.1 mm (0.004 in.). (f) Wing venation of a typical…
Image
from article Psocoptera
Liposcelis brunnea, female (family Liposcelididae): habitus of a cleared specimen. Body length: 1.1 mm (0.043 in.).
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from article Psittaciformes
Sulphur-crested cockatoo (Cacatua galerita). (Photo by Lloyd Glenn Ingles; copyright © California Academy of Sciences)
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from article Strigiformes
Northern spotted owl. (Photo by John and Karen Hollingsworth/U.S. Fish and Wildlife Service)
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from article Sloth
Pale-throated three-toed tree sloth (Bradypus tridactylus). (Credit: Lloyd Glenn Ingles; copyright © California Academy of Sciences)
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from article Chameleon
A short-horned chameleon (Calumma brevicorne, family Chamaeleonidae), which is a representative species found in Madagascar. (Credit: Gerald and Buff Corsi; copyright © California Academy of Sciences)
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from article Stichosomida
Anterior end of Trichinella spiralis showing stichosome. (Adapted from B. G. Chitwood, 1930)
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from article Stichosomida
Portion of the stichosome of the whipworm, Trichuris trichiura. (Photomicrograph by Sung-Jong Hong, The Korean Society for Parasitology)
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from article Centrohelida
Centrohelida. (a) Raphidiophrys ambigua. (b) Acanthocystis erinaceoides.
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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
Image
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).
Image
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 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 Albuliformes
Albula vulpes. (Courtesy of C. Q. Jessen)
Image
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…
Image
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 Velatida
Abactinal surface of Pteraster tesselatus. (In radially symmetrical animals, the abactinal surface pertains to the surface opposite the side where the mouth is located.)
Image
from article Velatida
Cross section through an arm of Pteraster tesselatus, showing the supradorsal membrane (SD) and tube feet (TF).
Image
from article Velatida
Abactinal surface of Solaster endeca.
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from article Volvocida
Carteria, showing equal plural flagella.
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from article Volvocida
Morphological features of Volvox. (a) Volvox globator, sectional view; (b) surface view of a single zooid. (c) Volvox aureus, sectional view; (d) sperm, enlarged about eight times by comparison with c.
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from article Respiratory pigments (invertebrate)
Electron micrograph of hemocyanin molecules from the snail Helix pomatia, showing “pillbox” subunit structure. Circular forms show subunits in a tenfold symmetrical array. There are six parallel rows of subunits in the rectangular forms.
Image
from article Gasterosteiformes
Alligator pipefish (Syngnathoides biaculeatus). (Photograph copyright © J. E. Randall)
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from article Reptilia
Desert tortoise (Gopherus agassizii). (Credit: Robb Hannawacker/National Park Service)
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from article Reptilia
Western or variable ground snake (Sonora semiannulata). (Credit: Peter Paplanus)
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from article Reptilia
Greater short-horned lizard (Phrynosoma hernandesi). (Credit: Lake Mead National Recreation Area, Arizona–Nevada/National Park Service)
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from article Pegasidae
Short (little) dragonfish (Eurypegasus draconis) found in the waters off the Tayandu Islands, Indonesia. (Photo by Teddy Triandiza)
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from article Rotifera
Common species from the three rotifer groups. (a) The seisonid Seison nebaliae. (b) The bdelloid Philodina roseola. (c) The monogonont Brachionus plicatilis.
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from article Rotifera
Four of the 8 or 9 recognized types of rotifer mastax. (a) Forcipate mastax of the monogonont Albertia vermiculus has all parts of the mallei and incus. (b) Incudate mastax of the monogonont Asplanchna brightwellii has enlarged, pincerlike rami and…
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from article Rotifera
Life cycles of the three rotifer groups. (a) Gonochoristic reproduction in seisonids. (b) Parthenogenesis alternating with sexual reproduction in monogononts. (c) Obligate parthenogenesis in bdelloids. 2n represents diploidy, and n represents…
Image
from article Calcarea
A calcareous sponge belonging to the family Leucettidae (order Clathrinida). (Credit: Bernard Dupont)
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from article Calcarea
Grades of construction of the water-current system in Calcarea: (a) asconoid type; (b) syconoid type without cortex; (c) syconoid type with cortex; (d) intermediate or transitional stage between syconoid and leuconoid types; (e) leuconoid type.…
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from article Calcarea
Spicule formation in the calcareous sponges: (a, b, c) early stages in secretion of the triactine spicule; (d) late stage of spicule formation. (Copyright © McGraw-Hill Education)
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from article Remipedia
Representative Remipedia. (a) Speleonectes lucayensis (after F. R. Schram, Crustacea, Oxford University Press, New York, 1986). (b) Lasionectes entrichoma [after J. Yager and F. R. Schram, Lasionectes entrichoma, new genus, new species (Crustacea:…
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from article Cumacea
A typical adult male cumacean.
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from article Coronoidea
Stephanocrinus gemmiformis, Middle Silurian, Tennessee; side view of the theca.
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from article Macrostomorpha
Macrostomum lignano, a new species from the northern Adriatic near Lignano, Italy. (a) Photomicrograph of a living, slightly squeezed worm. (b) Diagram showing the major organ systems. (From L. Schärer, G. Joss, and P. Sandner, Mating behavior of…
Image
from article Myzostomida
Scanning electron microscopy view of the ventral side of the Indo-Pacific Myzostoma ambiguum showing the parapodia and the marginal cirri. The individual is 4 mm (0.16 in.) long.
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from article Myzostomida
Scanning electron microscopy view of the ventral side of the Atlantic Myzostoma cirriferum metatrochophore. The larva is 0.05 mm (0.002 in.) long.
Image
from article Killer whale
Killer whales (Orcinus orca) in the waters off Alaska. (Credit: David Ellifrit/Alaska Fisheries Science Center, National Oceanic and Atmospheric Administration)
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from article Killer whale
The tail of a killer whale. (Credit: Janice Waite/Alaska Fisheries Science Center, National Oceanic and Atmospheric Administration)
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from article Grylloblattodea
Dorsal view of the first ice crawler species to be described: Grylloblatta campodeiformis. (Redrawn from the original paper by E. M. Walker, A new species of Orthoptera, forming a new genus and family, Can. Entomol., 46(3):93–99, 1914)
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from article Mink
American mink (Neovison vison; alternatively, Mustela vison). (Photo courtesy of Isle Royale National Park, Michigan; U.S. National Park Service)
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from article Stickleback
Nine-spine stickleback (Pungitius pungitius). (Photo by Konrad P. Schmidt)
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from article Stickleback
Three-spine stickleback (Gasterosteus aculeatus). (Bob Jenkins and Noel Burkhead; EFISH )
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from article Lepisosteiformes
Spotted gar (Lepisosteus oculatus). (Photo by Brian Montague, U.S. Fish and Wildlife Service)
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from article Euglenida
Euglenids. (a) Euglena pisciformis. (b) Phacus strokesii. (c) Cross section of cell.
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from article Trilobita
Two iron-stained trilobites (Paradoxides) on a bedding plane slab from Morocco, North Africa, of Cambrian age. (Credit: Alan Morgan)
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from article Trilobita
Trilobite diversity and preservation. (a) Olenellid, Lower Cambrian (British Columbia). External mold of exoskeleton in shale. (b) Ogygopsis, Middle Cambrian (British Columbia). Molt assemblage, with cranidium and pygidium aligned, but librigenae,…
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from article Trilobita
Morphological features of trilobites. (a) Calymene, Silurian (New York). Dorsal view of mineralized exoskeleton. (b) Phacops, Devonian (Ohio). Ventral (bottom) view of cephalon and anterior segments of the thorax, with hypostome attached. (c)…
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from article Trilobita
Triarthrus eatoni, Upper Ordovician (New York). Reconstruction with dorsal exoskeleton removed on right side to show appendages. Antennae are incomplete. Exites (gill branches) of the first nine postantennal appendages are removed to show the…
Image
from article Neomeniomorpha
Gymnomenia virgulata Scheltema from a depth of 620 m (2000 ft) off Walvis Bay, Namibia. (a) Entire specimen, anterior to right, long cilia extending from the pedal pit. (b, c) Posterior and anterior ends, respectively. (d) Ventral view of a,…
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from article Monoplacophora
Living and fossil Monoplacophora. (a) Neopilina galatheae. (b) Tryblidium reticulatum. (After R. C. Moore, ed., Treatise on Invertebrate Paleontology, pt. I, 1957)
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from article Monoplacophora
Side views of various helcionellacean and bellerophont univalved mollusks. (a) Cyrtonellopsis; (b) Hypseloconus; (c) Cyclocyrtonella; (d) Stenotheca; (e) Bellerophon; (f) Tropidodiscus. (After B. Runnegar, Class Monoplacophora, in R. S. Boardman, A.…
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from article Gorgonacea
Gorgonian colonies in life. (a) Plumigorgia cf. hydroides, Palawan, Philippines. (b) Eunicella gracilis, São Tomé, Gulf of Guinea. (c) Junceella fragilis, Luzon, Philippines. (d) Leptogorgia alba, Cocos Island, Costa Rica. (e) Astrogorgia sp.,…
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from article Gorgonacea
Some common gorgonaceans. (a) Thouarella hicksoni (inset, detail of polyps). (b) Ideogorgia capensis. (c) Eunicella papillosa. (d) Leptogorgia lutkeni. (e) Junceella sp. (f) Anthothela parviflora. (g) Rumphella sp. (h) Homophyton verrucosum. (i)…
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from article Gorgonacea
Gorgonian colonies (dry preserved specimens). (a) Briareum sp. (b) Ideogorgia capensis. (c) Chrysogorgia pinnata. (d) Fanellia compressa. (e) Viminella sp. (f) Paragorgia sp. (g) Subergorgia suberosa. (h) Isis hippuris. (i) Solenocaulon sp.
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from article Gorgonacea
Caribbean gorgonian colonies (digital scans from dry preserved specimens). (a) Muricea cf. fruticosa. (b) Gorgonia ventalina. (c) Pseudopterogorgia cf. hummelincki.
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from article Gorgonacea
Gorgonian colonies (dry preserved specimens). (a) Leptogorgia palma. (b) Skeleton of Isidella sp. (Artwork courtesy of Jessica Machnicki, California Academy of Sciences)
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from article Gorgonacea
Gorgonian morphology.
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from article Polycladida
Examples of body form in acotylean polyclads. (a) A more common oval shape with midventral mouth and pharynx (Stylochus ellipticus). (b) A less common ribbon shape with a posteriorly positioned mouth and pharynx (Latocestus whartoni). (Illustration…
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from article Polycladida
Anatomy of Pleioplana atomata, a common acotylean polyclad of temperate waters. (Illustration courtesy of L. H. Hyman)
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from article Polycladida
Cycloporus, a large cotylean polyclad with anal pores. (Illustration courtesy of L. H. Hyman)
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from article Elephant
The African bush elephant (Loxodonta africana). (Credit: Robert Thomas and Margaret Orr; copyright © California Academy of Sciences)
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from article Heterocorallia
Morphology of the heterocorallian skeleton. (a) External view. (b) Transverse thin section. (c) Median longitudinal thin section. (d) Enlarged part of c. (After R. C. Moore, ed., Treatise on Invertebrate Paleontology, pt. F, Geological Society of…
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from article Heterocorallia
Details of the heterocorallian body. (a) Generalized pattern of septal insertion (from O. Schindewolf, Grundfragen der Paläontologie, Schweizerbart, Stuttgart, 1950). (b) Reconstruction of the mesenterial in the soft body (from M. Gudo,…
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from article Sable
Sable (Martes zibellina). (Photo courtesy of Alex Kantorovich)
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from article Selachii
Caribbean reef shark (Carcharhinus perezi), a species of ground shark. (Getty Images copyright © Digital Vision)
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from article Llama
The llama (Lama glama) of South America. (Copyright © McGraw Hill)
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from article Platypus
Platypus, a primitive aquatic mammal. (Photograph by Paddy Ryan/Ryan Photographic)
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from article Acanthometrida
Acanthometra. (Credit: Based on an original illustration by L. H. Hyman; copyright © McGraw-Hill Education)
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from article Sarcodina
Some shelled Lobosia. (a) Arcella, seen from above; (b) sporulating into numerous ameboid young; (c) in binary fission, with the two nuclei in mitosis with polar caps; part of the cytoplasm exudes from the pylome and secretes a new shell. (d)…
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from article Paleocopa
Paleocopa. (a) Ogmoopsis nodulifera, left valve; from the Ordovician of Sweden. (b) Eurychilina subradiata, right valve showing wide complete frill; Ordovician of Minnesota. (c) Sulcicuneus porrectinatium, male and female carapaces; Devonian of…
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from article Podocopida
Candona suburbana, an ostracod of the Cypridoidea. Animals with right valves removed. (a) Female; note dimorphic differences in carapace outline and first leg. (b) Male with hemipenis rotated, folded, and retracted; part of the body wall is removed…
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from article Podocopida
Limnocythere sanctipatricii, a podocopid ostracod of the Cytheroidea. (a) Male with left valve removed; the paired hemipenes occupy much of the space at the rear of the carapace. (b) Male left “brush-shaped organ,” an unusual structure found only…
