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Animals / Wildlife: Most Popular Articles

These articles are the most popular over the last month.
Understand These 6 Groups, and You Can...
An introduction to the six basic groups of animals including amphibians, birds, fishes, invertebrates, mammals, and reptiles.
10 Fascinating Facts about Owls
Facts about owls, a group of birds known for their distinct calls, nocturnal habits, and silent flight.
The 10 Largest Living Mammals
A list of the largest species in each group of mammals that inhabit our planet today.
Animal Profiles - An A to Z List of Common Names
An A to Z list of animal profiles available in The Animal Encyclopedia, sorted alphabetically by common name.
Mammal Profiles - An A to Z List of Mammals
The following is an A to Z list of mammal profiles available, sorted alphabetically.
Top 10 Wildlife Conservation Organizations
A list of my top ten favorite conservation organizations that work to protect animals and wildlife around the world.
An A to Z Index of Animal Profiles and Facts
An A to Z list of animal profiles available in The Animal Encyclopedia, sorted alphabetically by scientific name.
The 8 Key Characteristics of Mammals
Learn about the key characteristics of mammals including mammary glands, hair, endothermy, diphyodonty, and more.
8 Simple Things You Can Do to Protect Animals
A list of simple things you can do to help protect animals and wildlife.
What Are Arthropods?
Profile of arthropods, a group of invertebrates that includes insects, spiders, crustaceans, scorpions, centipedes, and many others.
What Characteristics Make an Animal an Animal?
Learn about the key characteristics of animals including multicellularity, eukaryotic cells, sexual reproduction, movement, and more.
Cnidarian Characteristics
Cnidarians are diverse and come in many shapes and sizes but there are some basic features of their anatomy that most members of the group share in common.
10 Curious Creatures from the Amazon River Basin
A list of ten animals of the Amazon River basin in South America including harpy eagles, three-toed sloths, toucans, and more.
Facts About Bears
Facts about bears, a group of carnivores known for their burly build, impressive agility and, in some species, their winter sleep habits.
What's the Difference Between Prokaryote and...
All living organisms can be sorted into one of two groups depending on the fundamental structure of their cells. These two groups are the prokaryotes and the eukaryotes.
Facts You Should Know About Birds
Facts about birds, a group of vertebrates that includes nearly 10,000 species that are unique for their feathers and furculas, also know as wishbones.
Facts About Dolphins
Learn interesting facts about dolphins and find out about the characteristics make them different from other animal groups, their life cycle and their evolutionary history.
10 Little-Known Facts About Giraffes
Facts about giraffes, a group of mammals that are best known for their tall profile, long neck, and the distinct patchwork pattern of their fur.
Molluscs
Profile of molluscs, a group of invertebrates that includes squid, octopuses, cuttlefish, nudibranchs, snails, slugs, limpets, mussels, and many more.
Cnidarians
Profile of cnidarians, a group of aquatic invertebrates that includes jellyfish, corals, sea anemones and hydras.
Facts About Jellyfish
Learn interesting facts about jellyfish and find out about the characteristics make them different from other cnidarian groups, their life cycle and their evolutionary history.
Beyond the Arms: 11 Facts about Octopi:
From clouds of ink to chromatophores, there's more to octopi than eight arms.
The Basic Mammal Groups
An introduction to the basic mammal groups including aardvarks, bats, carnivores, cetaceans, elephants, marsupials, primates, rodents, and many others.
Facts About Great Horned Owls
Learn interesting facts about great horned owls and find out about the characteristics make them different from other animal groups, their life cycle and their evolutionary history.
Lions, Tigers, Leopards, Cheetahs and Other Cats
In this photographic guide, find out more about cats, their classification, adaptations, and natural history.
Facts About Amphibians
Learn facts about frogs and find out about their diversity, evolutionary history and the characteristics make them different from other vertebrates.
How Many Animal Species Inhabit Our Planet?
An article examining how scientists estimate and count the number of animals that live on our planet today.
Facts About Arthropods
In this article, you'll learn interesting facts about arthropods and find out about their unique characteristics, their life cycle and their evolutionary history.
The Basics of Vertebrate Evolution
An overview of vertebrate evolution that explores the key developments in the evolution of mammals, birds, reptiles, amphibians, and fish.
7 Kinds of Animals Found at the Great Barrier...
A list of some of the animals that inhabit the Great Barrier Reef including sea birds, mollusks, marine mammals, marine reptiles, and more.
Facts About Mammals
Learn interesting facts about mammals and find out about their diversity, evolutionary history and the characteristics make them different from other animal groups.
Facts About Reptiles
Learn interesting facts about reptiles and find out about their diversity, evolutionary history and the characteristics make them different from other animal groups.
The Life Cycle of a Jellyfish
The most recognized image of a jellyfish is that of the adult jellyfish, with its bell-shaped body and long tentacles.
An Introduction to Evolution
A brief overview of the history of life from the time the first life evolved until the present day. Page 2.
Habitat Destruction
Definition of habitat destruction, a term that is used to describe the process by which natural habitat is damaged or destroyed.
Facts About Snowy Owls
Learn interesting facts about snowy owls and find out about the characteristics make them different from other owls, their life cycle and their evolutionary history.
Facts About Molluscs
Molluscs are invertebrates that include animals such as squid, octopuses, cuttlefish, nudibranchs, snails, slugs, limpets, sea hares, mussels, clams, oysters, scallops, as well as many lesser known creatures.
Facts About Invertebrates
Learn interesting facts about invertebrates and find out about their diversity, evolutionary history and the characteristics make them different from other animal groups.
Facts About Zebras
Facts about zebras, a group of equids with a distinct black and white striping pattern.
Ten Animals of North America
A list of some of the animals that inhabit North America including the nine-banded armadillo, tufted titmouse, caribou, monarch butterfly, and more.
The Life Cycle of a Frog
The life cycle of a frog consists of three stages: egg, larva, and adult. As the frog grows it moves through these stages in a process known as metamorphosis. Page 4.
Mammals
Profile of mammal, a group of four-legged vertebrates that have hair, a four chambered heart and mammary glands.
Echinoderms
Profile of echinoderms, a diverse group of marine invertebrates comprising approximately 6000 species.
Descent with Modification
Descent with modification refers to the passing on of traits from parent organisms to their offspring.
What Do Turtles Eat?
Turtle eating habits are varied—what they eat depends on the available food sources, the habitat in which the turtle lives and the turtle's behavior.
Insects
Profile of insects, a highly successful group of animals that accounts for more species of animals than any other class of animals.
Niche
Definition of a niche, a term used to describe the role an organism or population plays within its community or ecosystem.
The Basic Amphibian Groups
An introduction to the three basic groups of amphibians including salamanders and newts, caecilians, and frogs and toads.
Chordates
Profile of chordate, a group of animals that includes vertebrates, tunicates, lancelets.
Elephant Trunk
Elephants' trunks are muscular, flexible extensions of their upper lip and nose. The tip of an African elephant's trunk has two fingerlike growths that enables them to grasp food and other small objects.
Lion Pride
Definition of lion pride, a term that refers to a group of line that typically includes about five females and two males and their young.
Heterotroph
A heterotroph is an organism that is unable to obtain its carbon from carbon dioxide. Instead, heterotrophs obtain carbon from organic material such as other organisms, living or dead.
Endangered Species
Definition of endangered species, a term used to refer to a species in danger of extinction throughout all or a significant portion of its range.
Top 10 Cutest Birds
Of all animals, birds are among the most varied in color, shape and size. In this gallery we'll catch a glimpse of a small handful of the many birds that can claim to be the cutest of their kind.
Facts About Frogs
Learn interesting facts about frogs and find out about their diversity, evolutionary history and the characteristics make them different from other amphibian groups.
Amphibians Amphibia salamanders newts...
Profile of amphibians, a group of vertebrates that includes frogs and toads, caecilians, and newts and salamanders.
Storming the Beaches
The vertebrates that underwent the evolutionary transition from life in water to life on land faced four basic adaptive challenges
Facts About Fishes
Learn interesting facts about fishes and find out about their diversity, evolutionary history and the characteristics make them different from other animal groups.
The Basic Invertebrate Groups
An introduction to six basic groups of invertebrates including arthropods, cnidarians, echinoderms, mollusks, segmented worms, and sponges.
Sponges Porifera Hexactinellida Demospongiae...
Profile of sponges, a group of simple aquatic invertebrates that include glass sponges, demisponges, and calcareous sponges.
Crazy Facts About Sharks, Rays, and Skates
Profile of cartilaginous fishes, a group of fishes that includes the largest and most formidable marine predators alive today.
Reptiles
Profile of reptiles, a group of vertebrates that colonized terrestrial habitats more extensively than their amphibian ancestors.
Lion Pictures
Lions are the largest of all African cats. They are the second largest cat species worldwide, smaller than only the tiger. Lions range in color from nearly white to tawny yellow, ash brown, ochre, and deep orange-brown. They have a tuft of dark fur at the tip of their tail.
Bony Fishes
Profile of bony fishes, a group of vertebrates characterized by having a bony skeleton unlike the cartilaginous fishes whose skeleton consists of cartilage.
Lion
Profile of the lion, a species of large cat that has a buff colored coat, white underparts, and a long tail that ends in a black tuft of fur.
Facts About Marsupials
Learn interesting facts about marsupials and find out about the characteristics make them different from other animal groups, their life cycle and their evolutionary history.
What Is a Keystone Species?
A keystone species is a species that plays a critical role in maintaining the structure of an ecological community and whose impact on the community is greater than would be expected based on its relative abundance or total biomass.
Surprising Facts About Snails, Squids, and...
Molluscs are a group of invertebrates known for their remarkable diversity—both sheer number of species as well as variety of form. Learn interesting facts about mollusks and find out about the characteristics make them different from other animal groups.
Tiger
Profile of tigers, the largest and most powerful of all cats that have a distinct orange coat, black stripes and white markings.
Species
The term species can be defined as a group of individual organisms that are capable of interbreeding to produce fertile offspring in nature.
Bird Characteristics
Bird characteristics include numerous adaptations for flight such as feathers, a furcula and hollow bones. This article explores the key characteristics that together distinguish birds from other animal groups.
Jellyfish
Profile of jellyfish, a group of carnivorous cnidarians with a bell-shaped body and tentacles.
The Basic Bird Groups
An introduction to the 30 basic groups of birds including birds of prey, buttonquails, gamebirds, herons, hummingbirds, owls, rheas, and many others.
Harvestmen
Harvestmen are a group of arachnids that include more than 6,300 species. This profile explores basic facts about harvestmen including their classification, diet, habitat and what makes them different from other arachnids.
Communities and Ecosystems
The natural world is characterized by many complex interactions and relationships between animals, plants, and their environment. Individual belong, in turn, to populations, species, communities, and ecosystems.
Carnivores
Profile of carnivores, a group of mammals that includes dogs and their relatives, bears, racoons, mustelids, civits, hyenas, aardwolf, and cats.
What Is Sexual Dimorphism?
Sexual dimorphism is the difference in form between male and female members of the same species.
Birds
Birds are vertebrates that have four limbs, wings, feathers, hollow bones and other adaptations for an aerial lifestyle.
The Basic Reptile Groups
An introduction to the four basic groups of reptiles including crocodilians, lizards, snakes and turtles.
Endangered Animals
Endangered animals are species or populations that are at risk of becoming extinct.
A Guide to Vertebrates and Invertebrates
One criteria by which all animals are described is whether or not they have a backbone. This article explores facts about vertebrates and invertebrates.
Facts About Animals
Learn interesting facts about animals and find out about the characteristics make them different from other groups of living organisms.
Animals
Animals are multicellular organisms that are capable of locomotion and rely on other organisms to obtain their nourishment.
A Guide to Buying Binoculars
A guide to the different kinds of binoculars and their many features. Page 2.
Deciduous Forest
Profile of the deciduous forest, a type of forest in which the trees shed their leaves during the cold months of the year.
Elephants
Profile of elephants, a group of mammals that are noted for their large size, massive skull, and long muscular trunk.
Fun Facts About Some of Earth's Weirdest Animals
Profile of armadillos, sloths, and anteaters, a group of mammals that are notable for the unique joints in their backbone.
Vipers
Profile of vipers, a group of snakes that include true vipers, bush vipers, rattlesnakes, pit vipers, adders and night adders.
Arctic Wolf
Profile of the Arctic wolf, a subspecies of grey wolf that lives in the Canadian Arctic, Alaska, and northern Greenland.
Quiz - 6 Basic Animal Groups
Put your animal identification skills to the test in this quiz.
Cephalopods
Cephalopods are a group of mulluscs that include octopuses, cuttlefish, squid and the chambered nautilus. This profile explores basic facts about cephalopods including how they are classified, what they eat, where they live and the characteristics that make them different from other mollusc groups.
Appalachian Mountains
Profile of the Appalachian Mountain Range, an ancient band of mountains that stretches in a southwestern arc from Newfoundland to Alabama.
Population Biology
Populations are groups of individuals belonging to the same species that live in a shared region at the same time.
Classification of Cats
Cats belong to the group of vertebrates known as mammals. Within the mammals cats are classified with other meat eaters in the Order Carnivora (known commonly as 'carnivores'). Page 3.
African Elephant
Profile of the African elephant, the largest living land mammal and one three species of elephants alive today.
Cats of Africa - Caracal, Serval, Cheetah,...
The cats of Africa include the caracal, serval, cheetah, lion, and leopard. Page 8.
Tiger Pictures
Tigers are the largest and most powerful of all cats. They are extremely agile despite their bulk and can leap between 8 and 10 meters in a single bound. They are also among the most recognizable of cats thanks to their distinct orange coat, black stripes and white markings.
Cats
Cats inhabit a wide variety of habitats including coasts, deserts, forests, grasslands, and mountains.
Animals and Their Environment
A first step to understanding individual animals, and in turn populations of animals, is to understand the relationship they have with their environment.
Reptile Characteristics
What is a reptile? To answer this question, we must understand the characteristics of reptiles - such as amniotic eggs, scales and ectothermy.
Clean Air Act
The Clean Air Act was first enacted in 1970 and authorized the establishment of federal and state regulations that limit emissions stationary and mobile sources of air pollutants.
Feather Anatomy and Function
Feathers are a unique adaptation of birds. Feathers are made up of keratin, an insoluble protein that is also found in mammalian hair and reptilian scales.
The Basic Fish Groups
An introduction to the basic fish groups including bony fishes and cartilaginous fishes.
What Do Reptiles Eat?
Most reptiles are carnivores that feed on small invertebrates, mammals and other reptiles. A few reptiles are herbivores that feed on plant material as varied as grasses, fruits, shrubs and marine plants such as algae and kelp.
Understanding the Threats to Animals and Wildlife
Living things face a constant barrage of external stresses or threats that challenge their ability to survive and reproduce. If a species is unable to successfully cope with these threats through adaptation, they may face extinction.
Bivalves
Profile of bivalves, a group of molluscs that include clams, scallops, oysters, mussels, borers, trough shells and many others.
Why We Should Worry About Desertification
Desertification is the development of desert-like conditions in regions that have experienced human disturbance such as deforestation, overgrazing, or poorly managed agriculture.
Gastropods
Profile of gastropods, a group of molluscs that undergo torsion when they develop and have a spirally coiled shell.
A Guide to Cats
Adaptations of Cats. Animals / Wildlife. Page 2.
Tetrapod
A tetrapod is an animal with four limbs or whose ancestors had four limbs. Tetrapods include four of the six main groups of animals: amphibians, reptiles, mammals, and birds.
Organ Systems in Animals
Animals' bodies are made up of various organ systems, groups of organs that work together to perform a function.
Florida Panther Pictures
Pictures of Florida panthers, an endangered subspecies of panther that scientists believe are healthier and fitter than they were fifteen years ago. They have higher genetic diversity, better immunity to disease, and fewer genetic abnormalities. They suffer fewer heart defects, enjoy higher fertility and are better able to climb trees.
American Black Bear
Profile of the American black bear, a large carnivore that inhabits the forests, swamps, tundra throughout the more northerly reaches of North America.
Facts About Carnivores
Learn interesting facts about carnivores and find out about the characteristics make them different from other mammals, their life cycle and their evolutionary history.
Turtles
Profile of turtles, a group of reptiles best known for the hard shell which is a modification of their ribcage and vertebral column.
The Structure of a Forest
Mature forests often have several distinct layers including the forest floor, herb layer, shrub layer, understory, canopy, and emergents.
Mammalian Temperature Regulation
Does it surprise you that reindeer, who spend much time standing in snow, don't get cold feet? Likewise, dolphins, whose thin flippers glide constantly through cool water, seem to be just fine.
Quiz - Birds From Around the World
Put your bird identification skills to the test in this quiz.
How Do Tides and Waves Work?
Waves give rhythm to the ocean. They transport energy over vast distances. Where they make landfall, waves help to sculpt a unique and dynamic mosaic of coastal habitats.
What Is a Rain Shadow?
A rain shadow is an area of dry land on the leeward side of a mountain. This profile explores the geography, habitat, and wildlife of rain shadows.
Invertebrate
Definition of invertebrate, an animal that lacks a backbone. Invertebrates account for more than 97% of all species alive today.
The Largest Organisms on Earth
Giant sequoias, blue whales, Komodo dragons, African elephants all share the distinction of being among the world's largest organisms. Find out more about these and other sizeable creatures in this article examining the largest organisms on Earth.
Facts About Corals
Learn about corals and find out about their diversity, evolutionary history and the characteristics make them different from other invertebrate groups.
Amniote
Amniotes are a group of tetrapod vertebrates that have an egg (referred to as an amniotic egg) that is specially adapted to a terrestrial environment.
Squamates
Profile of squamates, a group of reptiles that sheds their skin periodically in patches and have uniquely jointed skulls and jaws.
Marsupials
Marsupials are a group of mammals that give birth to their young at an early stage of their development.
Snow Leopard Pictures
Snow leopards are mountain-dwelling cats that live throughout the ranges of South and Central Asia at altitudes between 9,800 and 16,500 feet. Snow leopards are classified as endangered and their population is declining due to habitat destruction and a dwindling prey base.
World Wildlife Fund
The World Wildlife Fund (WWF) is a global-scale conservation organization that works in 100 countries and consists of nearly 5 million members worldwide.
American Beaver
Profile of the American beaver, one of two living species of beavers and the world's second largest rodent, only the capybara of South America is larger.
Endangered Species FAQs
Endangered species are species that face a significant risk of extinction. Such species may be declining in number due to things such as habitat destruction, climate change, threats from invasive species.
Hogs and Pigs
Hogs and pigs, also known as suids, are a group of mammals that includes babirusas, pigs, warthogs, forest hogs, red river pigs, and bushpigs. The Family Suidae also includes the domestic pig, Sus scrofa. The Family Suidae is subdivided into eight genera containing a total of sixteen species of pigs.
Net Primary Production
Net primary production (NPP) is the total energy (or nutrients) accumulated by an ecological unit of interest (such as an organism, a population, or an entire community).
Polar Bear
The polar bear is among the largest land carnivores, comparable in size only to the brown bear. Polar bears weigh in the range of 400kg-680kg (880lb-1500lb) and are 2.1m-3.3m (7ft-11ft) in length.
The Nature Conservancy
Profile of The Nature Conservancy, a conservation group that works with governments, communities, and others to solve conservation challenges.
Owls
Profile of owls, a group of birds that have strong talons, a downward-curved bill, acute hearing, and keen eyesight.
Even-Toed Hoofed Mammals
Even-toed hoofed mammals include 225 species. The group is divided into three basic subgroups based on the anatomy of their stomach. These include the ruminants, pseudo ruminants and the non-ruiminants.
Segmented Worms
Segmented worms are bilaterally symmetrical invertebrates that include more than 12,000 species such as earthworms, ragworms and leeches. This profile explores basic facts about segmented worms including how they are classified, what they eat, where they live and the characteristics that make them different from other invertebrate groups.
Newts and Salamanders
Profile of newts and salamanders, slender bodied amphibians with a long tail and usually two pairs of limbs.
Animal Pictures - An A to Z List of Animal Photos
The following is an A to Z list of animal pictures available at this site, sorted alphabetically by common name.
The Evolutionary Lessons of Marsupials
By 110 million years ago, mammals had diverged into two distinct groups: the placental mammals-a group that includes humans and most modern mammals-and the marsupial mammals-a group that includes koalas, kangaroos, wombats, and pouched mice.
Invertebrates
Profile of invertebrates, animals that do not have a backbone or a bony skeleton.
Hares, Rabbits and Pikas
Hares, rabbits and pikas are small terrestrial mammals that include jackrabbits, cottontails, hares and pikas. This profile explores basic facts about hares, rabbits and pike including how they are classified, what they eat, where they live and the characteristics that make them different from other mammal groups.
Ecological Isolation
The isolation of competing species of organisms made possible by differences in each species food resources, habitat use, activity period, or geographical range.
How Do Coral Reefs Form?
Stony corals are a remarkable group of animals that inhabit tropical marine waters around the world and form vast colonies known as coral reefs
Amphibian Pictures
Pictures of amphibians including red-eyed tree frogs, axolotl, green tree frogs, California newts, leopard frogs, and more.
Fish
The term fish is used to refer to any aquatic vertebrate that has a skin covered with scales, two sets of paired fins, some unpaired fins, and a set of gills.
Plankton
Plankton are microscopic organisms that drift on the oceans' currents. They include organisms such as diatoms, dinoflagillates, krill, and copepods as well as the microscopic larva of crustaceans, sea urchins, and fish.
Animal Profiles - An A to Z List of Animal Groups
The following is an A to Z list of animal profiles available, sorted by animal group.
About Cheetahs, Lynxes, Caracal and Other Small...
The Subfamily Felinae, or the small cats, are a diverse group of carnivores. Page 4.
Amur Leopard
Profile of the Amur leopard, a subspecies of leopard and ranks among the world's most endangered cats.

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