Burung

Burung adalah anggota kelompok hewan bertulang belakang (vertebrata) yang memiliki bulu dan sayap. Fosil tertua burung ditemukan di Jerman dan dikenal sebagai Archaeopteryx.

Jenis-jenis burung begitu bervariasi, mulai dari burung kolibri yang kecil mungil hingga burung unta, yang lebih tinggi dari orang. Diperkirakan terdapat sekitar 8.800 – 10.200 spesies burung di seluruh dunia; sekitar 1.500 jenis di antaranya ditemukan di Indonesia. Berbagai jenis burung ini secara ilmiah digolongkan ke dalam kelas Aves.

Evolusi dan morfologi
Meskipun burung berdarah panas, ia berkerabat dekat dengan reptil. Bersama kerabatnya terdekat, suku Crocodylidae alias keluarga buaya, burung membentuk kelompok hewan yang disebut Archosauria.

Diperkirakan burung berkembang dari sejenis reptil di masa lalu, yang memendek cakar depannya dan tumbuh bulu-bulu yang khusus di badannya. Pada awalnya, sayap primitif yang merupakan perkembangan dari cakar depan itu belum dapat digunakan untuk sungguh-sungguh terbang, dan hanya membantunya untuk bisa melayang dari suatu ketinggian ke tempat yang lebih rendah.

Burung masa kini telah berkembang sedemikian rupa sehingga terspesialisasi untuk terbang jauh, dengan perkecualian pada beberapa jenis yang primitif. Bulu-bulunya, terutama di sayap, telah tumbuh semakin lebar, ringan, kuat dan bersusun rapat. Bulu-bulu ini juga bersusun demikian rupa sehingga mampu menolak air, dan memelihara tubuh burung tetap hangat di tengah udara dingin. Tulang belulangnya menjadi semakin ringan karena adanya rongga-rongga udara di dalamnya, namun tetap kuat menopang tubuh. Tulang dadanya tumbuh membesar dan memipih, sebagai tempat perlekatan otot-otot terbang yang kuat. Gigi-giginya menghilang, digantikan oleh paruh ringan dari zat tanduk.

Kesemuanya itu menjadikan burung menjadi lebih mudah dan lebih pandai terbang, dan mampu mengunjungi berbagai macam habitat di muka bumi. Ratusan jenis burung dapat ditemukan di hutan-hutan tropis, mereka menghuni hutan-hutan ini dari tepi pantai hingga ke puncak-puncak pegunungan. Burung juga ditemukan di rawa-rawa, padang rumput, pesisir pantai, tengah lautan, gua-gua batu, perkotaan, dan wilayah kutub. Masing-masing jenis beradaptasi dengan lingkungan hidup dan makanan utamanya.

Maka dikenal berbagai jenis burung yang berbeda-beda warna dan bentuknya. Ada yang warnanya cerah cemerlang atau hitam legam, yang hijau daun, coklat gelap atau burik untuk menyamar, dan lain-lain. Ada yang memiliki paruh kuat untuk menyobek daging (Elang), mengerkah biji buah yang keras (Burung manyar), runcing untuk menombak ikan (Burung Kormoran), pipih untuk menyaring lumpur (Bebek), lebar untuk menangkap serangga terbang (Burung kacamata biasa), atau kecil panjang untuk mengisap nektar (‘Ō‘ō Kaua‘i). Ada yang memiliki cakar tajam untuk mencengkeram mangsa, cakar pemanjat pohon, cakar penggali tanah dan serasah, cakar berselaput untuk berenang, cakar kuat untuk berlari dan merobek perut musuhnya.

Kebiasaan
Burung berkembang biak dengan bertelur. Telur burung mirip telur reptil, hanya cangkangnya lebih keras karena berkapur. Beberapa jenis burung seperti burung maleo dan burung gosong, menimbun telurnya di tanah pasir yang bercampur serasah, tanah pasir pantai yang panas, atau di dekat sumber air panas. Alih-alih mengerami, burung-burung ini membiarkan panas alami dari daun-daun membusuk, panas matahari, atau panas bumi menetaskan telur-telur itu; persis seperti yang dilakukan kebanyakan reptil.

Akan tetapi kebanyakan burung membuat sarang, dan menetaskan telurnya dengan mengeraminya di sarangnya itu. Sarang bisa dibuat secara sederhana dari tumpukan rumput, ranting, atau batu; atau sekedar kaisan di tanah berpasir agar sedikit melekuk, sehingga telur yang diletakkan tidak mudah terguling. Namun ada pula jenis-jenis burung yang membuat sarangnya secara rumit dan indah, atau unik, seperti jenis-jenis manyar alias tempua, rangkong, walet, dan namdur.

Anak-anak burung yang baru menetas umumnya masih lemah, sehingga harus dihangatkan dan disuapi makanan oleh induknya. Kecuali pada jenis-jenis burung gosong, di mana anak-anak burung itu hidup mandiri dalam mencari makanan dan perlindungan. Anak burung gosong bisa segera berlari beberapa waktu setelah menetas, bahkan ada pula yang sudah mampu terbang.

Jenis-jenis burung umumnya memiliki ritual berpasangan masing-masing. Ritual ini adalah proses untuk mencari dan memikat pasangan, biasanya dilakukan oleh burung jantan. Beberapa jenis tertentu, seperti burung merak dan cenderawasih, jantannya melakukan semacam tarian untuk memikat si betina. Sementara burung manyar jantan memikat pasangannya dengan memamerkan sarang setengah jadi yang dibuatnya. Bila si betina berkenan, sarang itu akan dilanjutkan pembuatannya oleh burung jantan hingga sempurna; akan tetapi bila betinanya tidak berkenan, sarang itu akan dibuang atau ditinggalkannya.

Burung dan manusia
Burung telah memberikan manfaat luar biasa dalam kehidupan manusia. Beberapa jenis burung, seperti ayam, kalkun, angsa dan bebek telah didomestikasi sejak lama dan merupakan sumber protein yang penting; daging maupun telurnya.

Di samping itu, orang juga memelihara burung untuk kesenangan dan perlombaan. Contohnya adalah burung-burung merpati, perkutut, murai batu dan lain-lain. Burung-burung elang kerap dipelihara pula untuk gengsi, gagah-gagahan, dan untuk olahraga berburu. Banyak jenis burung telah semakin langka di alam, karena diburu manusia untuk kepentingan perdagangan tersebut.

Selain itu populasi burung juga terus menyusut karena rusaknya habitat burung akibat kegiatan manusia. Oleh sebab itu beberapa banyak jenis burung kini telah dilindungi, baik oleh peraturan internasional maupun oleh peraturan Indonesia. Beberapa suaka alam dan taman nasional juga dibangun untuk melindungi burung-burung tersebut di Indonesia.

Yang menyenangkan, beberapa tahun belakangan ini telah tumbuh kegiatan pengamatan burung (birdwatching) di kalangan pemuda dan pelajar. Kegiatan yang menumbuhkan kekaguman dan kecintaan pada jenis-jenis burung yang terbang bebas di alam ini, sekaligus merintis kecakapan meneliti alam — terutama kehidupan burung — di kalangan generasi muda tersebut.

Macam-macam burung
* Ayam
* Burung Cenderawasih
* Burung Jalak
* Burung Kakatua
* Burung Merak
* Burung Merpati
* Burung Murai Batu
* Burung Murai Daun/Cucak ijo
* Burung Perkukut
* Burung Perenjak Jawa
* Burung Punai
* Merbah
* Pinguin
* Anis merah
* Anis Kembang
* Tledekan atau sulingan
* Cucak Rawa
* Cendet
* Branjangan
* Kacer
* Kenari
* Love Bird
* Decu
* Cendana

Perawatan burung berkicau
Untuk membuat burung peliharaan rajin berkicau, sehat, dan bulu-bulunya mengkilat, maka dapat dilakukan hal-hal sebagai berikut:

Pakan burung
Burung tangkaran banyak yang berasal dari alam, ataupun yang berasal dari anakan peternak. Bagi burung yang merupakan tangkapan dari alam, biasanya mereka agak liar, sehingga pola makan mereka lebih cenderung ke extra fooding (makanan-makanan hidup), bagi burung yang telah jinak biasanya mereka mau memakan poer/voer. Poer/Voer banyak yang dijual di pasaran, yang populer di Indonesia biasanya adalah merk Phoenix, Fancy, dan Gold Coin. Selain itu, terdapat banyak pula merk-merk yang lain.

Pagi hari
Kandang burung dikeluarkan ke teras rumah (diangin-anginkan). Akan lebih bagus jika digantung menghadap ke matahari terbit sambil membersihkan kandang dari fesenya kemudian berikan 2-3 ekor jangkrik yang sudah dibersihkan kakinya dan sayapnya ditambah kroto telur semut yang bersih sekitar 1 sendok teh. Kemudian mandikan Burung pada pukul 07.30.

Burung dapat disemprot menggunakan sprayer halus untuk membuat bulunya mengkilat. Sprayer tersebut dapat dicampur dengan air rebusan daun sirih atau shampo burung (biasa disebut Avi Shampoo) yang dijual umum di kios. Atau masukan wadah kecil yang di isi air bersih (dijual di kios juga). Apabila burungnya sudah terlatih, burung dapat dimasukan kekandang mandinya atau biasa disebut keramba mandi.

Setelah dibersihkan kandangnya dan dimandikan, kandang dan burungnya dapat dijemur dibawah matahari dari pukul 09.30 sampai dengan pukul 10.00. Kemudian angkat kandang burung dan gantung pada tempat yang teduh serta jauh dari aktivitas manusia agar burung tersebut bernyanyi/ berkicau.

Sore Hari (sekitar pukul 16.00)
Lakukan sama seperti perawatan pagi hari. Burung diberikan makanan tambahan, dimandikan kemudian dijemur kembali sampai bulu-bulunya kering.

Gajah

Famili Elephantidae (Gajah) adalah mamalia darat terbesar yang masih hidup, serta famili dari ordo Pachyderm, dan satu-satunya famili yang tersisa dari ordo Proboscidea.

Gajah adalah salah satu hewan yang ada di Indonesia. Gajah adalah mammalia dan merupakan hewan darat terbesar di dunia. Terdapat 2 spesies gajah di dunia yaitu:

1. Gajah Asia atau Gajah India (Elephas maximus).
2. Gajah Afrika (Loxodonta aricana).

Periode kehamilan gajah adalah 22 bulan, masa kehamilan terlama dibandingkan hewan darat lainnya.Berat anak gajah pada umumnya 120 kilogram dan seekor gajah bisa hidup selama kurang lebih 70 tahun.

Gajah juga pernah digunakan dalam peperangan sebagai gajah perang, yang digunakan untuk menyerang musuh. Gajah adalah satu-satunya mamalia di dunia yang tidak bisa melompat.

Spesies gajah
Gajah afrika merupakan hewan darat terbesar di dunia. Sepanjang 55 juta tahun terdapat 500 spesies gajah yang dikenal dan hanya dua spesies yang masih ada yaitu Gajah asia Elephas Maximus dan Gajah afrika Loxodonta Africana. Spesies Gajah asia dan Gajah afrika mulai terpecah kira-kira dua juta tahun dahulu. Gajah asia berbeda daripada Gajah afrika. Gajah asia memiliki telinga lebih kecil sedikit daripada Gajah afrika, mempunyai dahi yang rata, dan dua bonggol di kepalanya merupakan puncak tertinggi gajah, dibandingkan dengan Gajah afrika yang mempunyai hanya satu bonggol di atas kepala.Selain itu, ujung belalai Gajah Asia hanya mempunyai 1 bibir, sementara Gajah Afrika mempunyai 2 bibir di ujung belalai. Kedua jenis kelamin Gajah Afrika mempunyai gading sementara hanya Gajah Asia jantan yang mempunyai gading yang jelas kelihatan.

Ada pula spesies Gajah kerdil atau Pygmy ELephants dengan nama latin Elephas maximus borneensis adalah spesies terkecil gajah, bahkan lebih kecil dari Gajah Sumatra. Ukuran tubuhnya hanya sekitar 2,5 meter, seperti pada ukuran bayi gajah lainnya. Data menunjukkan bahwa DNA pada Gajah kerdil adalah sama sekali berbeda dari Gajah asia dan Gajah afrika, hal ini berarti bahwa Gajah kerdil merupakan subspesies baru dari gajah. Habitat tempat hidup mereka ada di kedalaman hutan Borneo, perbatasan antara Kalimantan Timur - Indonesia dengan Malaysia.

Karakteristik
Persebaran gajah di Asia meliputi India, Asia Tenggara termasuk Indonesia bagian barat dan Sabah (Malaysia Timur). Sedangkan gajah di Afrika persebarannya meliputi sebagian besar daratan Afrika yang berupa padang rumput. Di Indonesia, gajah terdapat di Sumatera (Gajah sumatera) dan di Kabupaten Nunukan, Kalimantan Timur (Gajah borneo).

Makanan
Gajah termasuk dalam kategori hewan herbivora. Ia menghabiskan 16 jam sehari untuk mengumpulkan makanan. Makanannya terdiri atas sedikitnya 50% rumput, ditambah dengan dedaunan, ranting, akar, dan sedikit buah, benih dan bunga. Karena gajah hanya mencerna 40% dari yang dimakannya, mereka harus mengkonsumsi makanan dalam jumlah besar. Gajah dewasa dapat mengkonsumsi 300 hingga 600 pon (140-270 kg) makanan per hari. Enam puluh persen dari makanan tersebut tertinggal dalam tubuh gajah dan tidak dicerna.

Reproduksi
Sebagai anggota dari kelas mammalia, gajah berkembangbiak dengan cara melahirkan dari masa kehamilan kurang lebih 22 bulan. Pada saat lahir, bayi gajah memiliki berat sekitar 120kg dengan tinggi 90cm, dan bayi gajah adalah salah satu bayi mammalia terbesar di dunia.

Perilaku sosial
Gajah hidup di dalam urutan sosial yang terstruktur. Kehidupan sosial dari jantan dan betina sangat berbeda.Betina menghabiskan hampir seluruh hidupnya di dalam satu kelompok keluarga yang terdiri atas ibu, anak perempuan, saudara perempuan, dan bibi.Kelompok ini dipimpin oleh gajah betina tertua dan ketika seekor gajah betina sedang mengandung, maka 2 - 3 gajah betina lainnya akan menemani hingga si ibu gajah melahirkan. Sedangkan jantan dewasa menghabiskan waktunya dalam kehidupan sendiri (tidak berkelompok).

Uniknya Gajah
Meskipun berbadan besar, gajah adalah hewan perenang yang handal. Mereka dapat berenang selama 6 jam dan menempuh jarak hingga 50 km.

Gading gajah yang besar merupakan sepasang gigi seri pada bagian depan rahang atas, yang terus tumbuh selama gajah hidup meskipun tidak tumbuh terlalu panjang.

Tengkorak gajah yang besar dan kuat, berisi otak yang sangat cerdas. Oleh karena itu, gajah mempunyai ingatan yang sangat baik dan jarang melupakan perintah - perintah yang telah diajarkan.Seekor gajah mampu mengingat 25 perintah atau aba - aba dan mampu membuat alat untuk digunakan sendiri, sebagai contoh, gajah akan mematahkan tonggak kayu untuk menggaruk punggungnya. Berkisah tentang seorang penulis Adriadne Oliver yang menuliskan cerita nyata mengenai pembongkaran kasus bunuh diri dua orang temannya 12 tahun yang lalu dibantu oleh detektif Belgia Hercule Poirot.

Kuburan Gajah
Menurut legenda, semua gajah di daerah tertentu, jika sudah tua, gajah akan pergi ke suatu tempat sendirian untuk menunggu malaikat maut menjemput ajalnya. Tempat itulah yang disebut dengan kuburan gajah dan konon di tempat ini tertimbun banyak sekali gading gajah yang sudah mati, jika kita berhasil menemukannya maka kita akan menjadi kaya.

Selama bertahun - tahun para petualang mencari kebenarannya, meskipun ditemukan kumpulan kerangka gajah, namun bukan berarti itu adalah kuburan gajah. Di Siberia telah ditemukan sejumlah besar gading gajah yang terkubur di dalam tumpukan salju, tetapi gading tersebut ternyata merupakan fosil milik mammoth (gajah purba) yang telah mati 10.000 tahun yang lalu.

Desas - desus mengenai kuburan gajah adalah tidak benar adanya, itu hanya merupakan legenda biasa. :D :P

Tikus

ikus adalah mamalia yang termasuk dalam suku Muridae. Spesies tikus yang paling dikenal adalah mencit (Mus spp.) serta tikus got (Rattus norvegicus) yang ditemukan hampir di semua negara dan merupakan suatu organisme model yang penting dalam biologi; juga merupakan hewan peliharaan yang populer.

Jenis-jenis penting
* mencit (Mus sp.)
* tikus rumah (Rattus rattus)
* tikus got (Rattus norvegicus)
* tikus sawah (Rattus argentiventer)
* wirok (Bandicota sp.)

Celurut (shrew), yang sering disebut sebagai "tikus", sesungguhnya bukanlah termasuk golongan hewan pengerat, melainkan hewan pemangsa serangga (Insectivora).

Cat

The cat (Felis catus), also known as the domestic cat or housecatto distinguish it from other felines and felids, is a small furry domesticated carnivorous mammal that is valued by humans for its companionship and for its ability to hunt vermin and household pests. Cats have been associated with humans for at least 9,500 years, and are currently the most popular pet in the world. Owing to their close association with humans, cats are now found almost everywhere in the world.

Cats are similar in anatomy to the other felids, with strong, flexible bodies, quick reflexes, sharp retractable claws, and teeth adapted to killing small prey. As nocturnal predators, cats use their acute hearing and ability to see in near darkness to locate prey. Not only can cats hear sounds too faint for human ears, they can also hear sounds higher in frequency than humans can perceive. This is because the usual prey of cats (particularly rodents such as mice) make high frequency noises, so the hearing of the cat has evolved to pinpoint these faint high-pitched sounds. Cats rely more on smell than taste, and have a much better sense of smell than humans.

Despite being solitary hunters, cats are a social species and use a variety of vocalizations, pheromones and types of body language for communication. These include meowing, purring, trilling, hissing, growling, and grunting.

Cats have a rapid breeding rate. Under controlled breeding, they can be bred and shown as registered pedigree pets, a hobby known as cat fancy. Failure to control the breeding of pet cats by spaying and neutering and the abandonment of former household pets has resulted in large numbers of feral cats worldwide, with a population of up to 60 million of these animals in the United States alone.

As The New York Times wrote in 2007, "Until recently the cat was commonly believed to have been domesticated in ancient Egypt, where it was a cult animal", but a study that year revealed that the lines of descent of all house cats probably run through as few as five self-domesticating African Wildcats (Felis silvestris lybica) c. 8000 BC, in the Near East.The earliest direct evidence of cat domestication is a kitten that was buried alongside a human 9,500 years ago in Cyprus.

Nomenclature and etymology
The word cat derives from Old English catt, which belongs to a group of related words in European languages, including Welsh cath, Spanish gato, French chat (French pronunciation: , Basque katu, Byzantine Greek Κάτια kátia, Old Irish cat, Frisian and Dutch kat, German Katze, Armenian katu, and Old Church Slavonic kotka. The ultimate source of all these terms is Late Latin catus, cattus, catta "domestic cat", as opposed to feles "European wildcat". It is unclear whether the Greek or the Latin came first, but they were undoubtedly borrowed from an Afro-Asiatic language akin to Nubian kadís and Berber kaddîska, both meaning "wildcat". The term puss (as in pussycat) may come from Dutch poes or from Low German Puuskatte, dialectal Swedish kattepus, or Norwegian pus, pusekatt, all of which primarily denote a woman and, by extension, a female cat.
While wildcats are the ancestral species from which domestic cats are descended, there are several intermediate stages between domestic pet and pedigree cats and these entirely wild cats. The semi-feral cat is a cat that is not owned by any one individual, but is generally friendly to people and may be fed by several households. Feral cats are associated with human habitations and may be fed by people or forage in rubbish, but are wary of human interaction. Pseudo-wildcats are descended from domestic cats, but now tend to live entirely independently from people.

A group of cats is referred to as a "clowder", a male cat is called a "tom" (or a "gib", if neutered), and a female is called a "molly" or "queen". The male progenitor of a cat, especially a pedigreed cat, is its "sire", and its female progenitor is its "dam". An immature cat is called a "kitten" (which is also an alternative name for young rats, rabbits, hedgehogs, beavers, squirrels and skunks).

In medieval Britain, the word kitten was interchangeable with the word catling. A cat whose ancestry is formally registered is called a pedigreed cat, purebred cat, or a show cat. In strict terms, a pure-bred cat is one whose ancestry contains only individuals of the same breed. A pedigreed cat is one whose ancestry is recorded, but may have ancestors of different breeds. Cats of unrecorded mixed ancestry are referred to as domestic longhairs and domestic shorthairs or commonly as random-bred, moggies, mongrels, or mutt-cats.

Taxonomy and evolution
The Felids are a rapidly evolving family of mammals that share a common ancestor only 10–15 million years ago, and include, in addition to the domestic cat, lions, tigers, cougars, and many others. Within this family, domestic cats (Felis catus) are part of the genus Felis, which is a group of small cats containing seven species. Members of the genus are found worldwide and include the Jungle Cat (Felis chaus) of southeast Asia, the African Wildcat (Felis silvestris lybica), the Chinese Mountain Cat (Felis silvestris bieti) and the Arabian Sand Cat (Felis margarita).

All the cats in this genus share a common ancestor that probably lived around 6–7 million years ago in Asia. Although the exact relationships within the Felidae are still uncertain, both the Chinese Mountain Cat and the African Wildcat are close relations of the domestic cat and are both classed as subspecies of the Wildcat Felis silvestris.As domestic cats are little altered from wildcats, they can readily interbreed. This hybridization may pose a danger to the genetic distinctiveness of wildcat populations, particularly in Scotland and Hungary.

The domestic cat was first classified as Felis catus by Carolus Linnaeus in the tenth edition of his Systema Naturae of 1758. However, because of modern phylogenetics, domestic cats are now usually regarded as another subspecies of the Wildcat Felis silvestris. This has resulted in mixed usage of the terms, as the domestic cat can be called by its subspecies name, Felis silvestris catus.Wildcats have also been referred to as various subspecies of F. catus, but in 2003 the International Commission on Zoological Nomenclature fixed the name for wildcats as F. silvestris. The most common name in use for the domestic cat remains F. catus, following a convention for domesticated animals of using the earliest (the senior) synonym proposed. Sometimes the domestic cat is called Felis domesticus or Felis domestica,the term coined by German naturalist Johann Christian Polycarp Erxleben in 1777. These are not valid taxonomic names, and Linnaeus' binomial takes precedence.

Cats have either a mutualistic or commensal relationship with humans. However, in comparison to dogs, cats have not undergone major changes during the domestication process, as the form and behavior of the domestic cat are not radically different from those of wildcats, and domestic cats are perfectly capable of surviving in the wild.This limited evolution during domestication means that domestic cats tend to interbreed freely with feral cats, which distinguishes them from other domesticated animals. However, several natural behaviors and characteristics of wildcats may have preadapted them for domestication as pets. These traits include their small size, social nature, obvious body language, love of play and relatively high intelligence; they may also have an inborn tendency towards tameness.

There are two main theories about how cats were domesticated. In one, people deliberately tamed cats in a process of artificial selection, as they were useful predators of vermin. However, this has been criticized as implausible, because there may have been little reward for such an effort: cats do not carry out commands and, although they do eat rodents, other species such as ferrets or terriers may be better at controlling these pests. The alternative idea is that cats were simply tolerated by people and gradually diverged from their 'wild' relatives through natural selection, as they adapted to hunting the vermin found around humans in towns and villages.

Dog

The dog (Canis lupus familiaris and Canis lupus dingo) is a domesticated form of the gray wolf, a member of the Canidae family of the order Carnivora. The term is used for both feral and pet varieties. The dog was the first animal to be domesticated, and has been the most widely kept working, hunting, and companion animal in human history. The word "dog" may also mean the male of a canine species, as opposed to the word "bitch" for the female of the species.

Dogs were domesticated from gray wolves about 15,000 years ago. They must have been very valuable to early human settlements, for they quickly became ubiquitous across world cultures. Dogs perform many roles for people, such as hunting, herding, pulling loads, protection, assisting police and military, companionship, and, more recently, aiding handicapped individuals. This impact on human society has given them the nickname "Man's best friend" in the western world. In 2001, there were estimated to be 400 million dogs in the world.

Over the 15,000 year span the dog had been domesticated, it diverged into only a handful of landraces, groups of similar animals whose morphology and behavior have been shaped by environmental factors and functional roles. Through selective breeding by humans, the dog has developed into hundreds of varied breeds, and shows more behavioral and morphological variation than any other land mammal. For example, height measured to the withers ranges from a few inches in the Chihuahua to a few feet in the Irish Wolfhound; color varies from white through grays (usually called "blue'") to black, and browns from light (tan) to dark ("red" or "chocolate") in a wide variation of patterns; coats can be short or long, coarse-haired to wool-like, straight, curly, or smooth. It is common for most breeds to shed this coat.

Etymology and related terminology
Dog is the common use term that refers to members of the subspecies Canis lupus familiaris (canis, "dog"; lupus, "wolf"; familiaris, "of a household" or "domestic"). The term can also be used to refer to a wider range of related species, such as the members of the genus Canis, or "true dogs", including the wolf, coyote, and jackals; or it can refer to the members of the subfamily Caninae, which would also include the African wild dog; or it can be used to refer to any member of the family Canidae, which would also include the foxes, bush dog, raccoon dog, and others. Some members of the family have "dog" in their common names, such as the raccoon dog and the African wild dog. A few animals have "dog" in their common names but are not canids, such as the prairie dog.

The English word dog comes from Middle English dogge, from Old English docga, a "powerful dog breed". The term may derive from Proto-Germanic *dukkōn, represented in Old English finger-docce ("finger-muscle"). The word also shows the familiar petname diminutive -ga also seen in frogga "frog", picga "pig", stagga "stag", wicga "beetle, worm", among others. Due to the archaic structure of the word, the term dog may ultimately derive from the earliest layer of Proto-Indo-European vocabulary, reflecting the role of the dog as the earliest domesticated animal.

In 14th century England, hound (from Old English: hund) was the general word for all domestic canines, and dog referred to a subtype of hound, a group including the mastiff. It is believed this "dog" type of "hound" was so common it eventually became the prototype of the category “hound”. By the 16th century, dog had become the general word, and hound had begun to refer only to types used for hunting. Hound, cognate to German Hund, Dutch hond, common Scandinavian hund, and Icelandic hundur, is ultimately derived from the Proto-Indo-European *kwon- "dog", found in Welsh ci (plural cwn), Latin canis, Greek kýōn, Lithuanian šuõ.

In breeding circles, a male canine is referred to as a dog, while a female is called a bitch (Middle English bicche, from Old English bicce, ultimately from Old Norse bikkja). A group of offspring is a litter. The father of a litter is called the sire, and the mother is called the dam. Offspring are generally called pups or puppies, from French poupée, until they are about a year old. The process of birth is whelping, from the Old English word hwelp, (cf. German Welpe, Dutch welp, Swedish valp, Icelandic hvelpur) .

Taxonomy
The domestic dog was originally classified as Canis familiaris and Canis familiarus domesticus by Carolus Linnaeus in 1758, and was reclassified in 1993 as Canis lupus familiaris, a subspecies of the gray wolf Canis lupus, by the Smithsonian Institution and the American Society of Mammalogists. Overwhelming evidence from behavior, vocalizations, morphology, and molecular biology led to the contemporary scientific understanding that a single species, the gray wolf, is the common ancestor for all breeds of domestic dogs; however, the timeframe and mechanisms by which dogs diverged are controversial. Canis lupus familiaris is listed as the name for the taxon that is broadly used in the scientific community and recommended by ITIS; Canis familiaris, however, is a recognised synomym.

History and evolution
Domestic dogs inherited a complex social hierarchy and behaviors from their wolf ancestors. Dogs are pack hunters with a complex set of behaviors related to determining each dog's position in the social hierarchy, and they exhibit various postures and other means of nonverbal communication that reveal their states of mind. These sophisticated forms of social cognition and communication may account for their trainability, playfulness, and ability to fit into human households and social situations, and these attributes have given dogs a relationship with humans that has enabled them to become one of the most successful species on the planet today.

Although experts largely disagree over the details of dog domestication, it is agreed that human interaction played a significant role in shaping the subspecies. Shortly after domestication, dogs became ubiquitous in human populations, and spread throughout the world. Emigrants from Siberia likely crossed the Bering Strait with dogs in their company, and some experts suggest the use of sled dogs may have been critical to the success of the waves that entered North America roughly 12,000 years ago,[citation needed] although the earliest archaeological evidence of dog-like canids in North America dates from about 9,000 years ago. Dogs were an important part of life for the Athabascan population in North America, and were their only domesticated animal. Dogs also carried much of the load in the migration of the Apache and Navajo tribes 1,400 years ago. Use of dogs as pack animals in these cultures often persisted after the introduction of the horse to North America.

The current consensus among biologists and archaeologists is that the dating of first domestication is indeterminate. There is conclusive evidence dogs genetically diverged from their wolf ancestors at least 15,000 years ago,but some believe domestication to have occurred earlier.[24] It is not known whether humans domesticated the wolf as such to initiate dog's divergence from its ancestors, or whether dog's evolutionary path had already taken a different course prior to domestication. For example, it is hypothesized that some wolves gathered around the campsites of paleolithic camps to scavenge refuse, and associated evolutionary pressure developed that favored those who were less frightened by, and keener in approaching, humans.

The bulk of the scientific evidence for the evolution of the domestic dog stems from archaeological findings and mitochondrial DNA studies. The divergence date of roughly 15,000 years ago is based in part on archaeological evidence that demonstrates the domestication of dogs occurred more than 15,000 years ago, and some genetic evidence indicates the domestication of dogs from their wolf ancestors began in the late Upper Paleolithic close to the Pleistocene/Holocene boundary, between 17,000 and 14,000 years ago. But there is a wide range of other, contradictory findings that make this issue controversial.

Archaeological evidence suggests the latest dogs could have diverged from wolves was roughly 15,000 years ago, although it is possible they diverged much earlier In 2008, a team of international scientists released findings from an excavation at Goyet Cave in Belgium declaring a large, toothy canine existed 31,700 years ago and ate a diet of horse, musk ox and reindeer.

Prior to this Belgium discovery, the earliest dog fossils were two large skulls from Russia and a mandible from Germany dated from roughly 14,000 years ago. Remains of smaller dogs from Natufian cave deposits in the Middle East, including the earliest burial of a human being with a domestic dog, have been dated to around 10,000 to 12,000 years ago. There is a great deal of archaeological evidence for dogs throughout Europe and Asia around this period and through the next two thousand years (roughly 8,000 to 10,000 years ago), with fossils uncovered in Germany, the French Alps, and Iraq, and cave paintings in Turkey. The oldest remains of a domesticated dog in the Americas were found in Texas and have been dated to about 9,400 years ago.