In most birds and reptiles, an egg (Latin ovum) is the zygote, resulting from fertilization of the ovum. Birds ( class Aves) are bipedal endothermic ( Warm-blooded) Vertebrate animals that lay eggs. Reptiles, or members of the class Reptilia are air-breathing Cold-blooded Vertebrates that have skin covered in scales as opposed to hair or feathers Latin ( lingua Latīna, laˈtiːna is an Italic language, historically spoken in Latium and Ancient Rome. For other meanings see Zygote (disambiguation. A zygote (from Greek ζυγωτός zugōtos "joined" or "yoked" For soil improvement see Fertilization (soil. An ovum (plural ova) is a Haploid Female reproductive cell or Gamete. To enable incubation the egg is usually kept within a favourable temperature range as it nourishes and protects the growing embryo. An embryo (from Greek:, plural, lit "that which grows" from en- "in" + bryein "to swell be full" is a multicellular When the embryo is adequately developed it breaks out of the egg in the process of hatching. Some embryos have a temporary egg tooth with which to crack or pip the eggshell or covering. In some egg -laying Animals the egg tooth is a small sharp cranial protuberance used by Offspring to break or tear through the egg's surface during
Oviparous animals are animals that lay eggs, with little or no other development within the mother. Oviparous animals are animals that lay eggs, with little or no other Embryonic development within the mother The study or collecting of eggs, particularly bird eggs, is called oology. Oology, or oölogy is the branch of Zoology that deals with the study of eggs especially Birds eggs
Reptile eggs, bird eggs, and monotreme eggs, which are laid out of water, are surrounded by a protective shell, either flexible or inflexible. The term eggshell is a term for the outer covering of a hard-shelled egg, and some forms of eggs with soft outer coats The special membranes that support these eggs are traits of all amniotes, including mammals. The amniotes are a group of Tetrapod Vertebrates that include the Synapsida ( Mammals and Mammal-like reptiles and Sauropsida Mammals ( class Mammalia) are a class of Vertebrate Animals characterized by the presence of Sweat glands, including sweat glands
The 1. 5 kg ostrich egg contains the largest existing single cell currently known, though the extinct Aepyornis and some dinosaurs had larger eggs. The Ostrich ( Struthio camelus) is a large Flightless bird native to Africa (and formerly the Middle East) Elephant birds are an extinct family of Flightless Birds comprising the genera Aepyornis and Mullerornis. The Bee Hummingbird produces the smallest known bird egg, which weighs half a gram. The Bee Hummingbird ( Mellisuga helenae) is a Hummingbird, and the smallest of all Birds It can be found in Cuba (where it is called the The eggs laid by some reptiles and most fish can be even smaller, and those of insects and other invertebrates can be much smaller still. An invertebrate is an Animal lacking a Vertebral column. The group includes 98% of all animal Species — all animals except those in the Chordate
Contents |
Bird eggs
Bird eggs are laid by females and incubated for a time that varies according to the species; a single young hatches from each egg. A nudibranch (pronounced (BrE or (AmE is a member of one Suborder of soft-bodied shell-less marine Opisthobranch Gastropod Mollusks The orange-peel doris, ( Acanthodoris lutea) is a Species of Nudibranch or sea Slug, a shell-less marine Opisthobranch California ( is a US state on the West Coast of the United States, along the Pacific Ocean. Tide pools (also tidal pools, rock pools or rock and roll pools) are rocky pools by Oceans that are filled with Seawater. Incubation is the process by which Birds hatch their eggs, and to the development of the Embryo within the egg Average clutch sizes range from one (as in condors) to about 17 (the Grey Partridge). A clutch of eggs refers to all the eggs produced by one Bird or Reptile at a single time particularly Condor is the name for two Species of New World vultures each in a Monotypic Genus. The Grey Partridge, Perdix perdix also known as the English Partridge, Hungarian Partridge or Hun is a Gamebird in the pheasant Some birds lay eggs even when not fertilized; it is not uncommon for pet owners to find their lone bird nesting on a clutch of infertile eggs, which are also called wind-eggs.
Colors
The default color of vertebrate eggs is the white of the calcium carbonate from which the shells are made, but some birds, mainly passerines, produce colored eggs. Calcium carbonate is a Chemical compound with the Chemical formula Ca[[Carbon C]] O 3 The pigments biliverdin and its zinc chelate give a green or blue ground color, and protoporphyrin produces reds and browns as a ground color or as spotting. Biliverdin is a green Pigment formed as a byproduct of Heme breakdown Chelation is the binding or complexation of a bi- or multidentate Ligand. Protoporphyrins are Tetrapyrroles containing the following Side chains Methyl (4 Propionic acid (2
Non-passerines typically have white eggs, except in some ground-nesting groups such as the Charadriiformes, sandgrouse and nightjars, where camouflage is necessary, and some parasitic cuckoos which have to match the passerine host's egg. Charadriiformes is a diverse order of small to medium-large Birds It includes about 350 Species and has members in all parts of the world Sandgrouse is also the name of the journal of the Ornithological Society of the Middle East - see Sandgrouse (journal The sandgrouse are a This article is about the bird For the aircraft see Gloster Nightjar. Brood parasites are organisms that use the strategy of brood-parasitism, a kind of Kleptoparasitism found among Birds Fish or Insects The cuckoos are a family Cuculidae, of Near passerine Birds The order Cuculiformes, in addition to the cuckoos also includes the Most passerines, in contrast, lay colored eggs, even if there is no need of cryptic colors.
However, a recent study suggests that the protoporphyrin markings on passerine eggs actually act to reduce brittleness by acting as a solid state lubricant. If there is insufficient calcium available in the local soil, the egg shell may be thin, especially in a circle around the broad end. Protoporphyrin speckling compensates for this, and increases inversely to the amount of calcium in the soil.
For the same reason, later eggs in a clutch are more spotted than early ones as the female's store of calcium is depleted.
The color of individual eggs is also genetically influenced, and appears to be inherited through the mother only, suggesting that the gene responsible for pigmentation is on the sex determining W chromosome (female birds are WZ, males ZZ). History See also History of genetics The existence of genes was first suggested by Gregor Mendel (1822-1884 who in the 1860s studied inheritance The ZW sex-determination system is a system that determines the sex of offspring in Birds, some Fish, and some Insects (including Butterflies
It used to be thought that color was applied to the shell immediately before laying, but this research shows that coloration is an integral part of the development of the shell, with the same protein responsible for depositing calcium carbonate, or protoporphyrins when there is a lack of that mineral.
In species such as the Common Guillemot, which nest in large groups, each female's eggs have very different markings, making it easier for females to identify their own eggs on the crowded cliff ledges on which they breed. The Common Guillemot or Common Murre ( Uria aalge) is a large Auk.
Shell
Bird eggshells are diverse. For example:
- cormorant eggs are rough and chalky
- tinamou eggs are shiny
- duck eggs are oily and waterproof
- cassowary eggs are heavily pitted
Tiny pores in bird eggshells allow the embryo to breathe. The Bird family Phalacrocoracidae is represented by some 40 Species of cormorants and shags. The tinamous are one of the most ancient groups of Bird, members of a South American Bird family of about 47 species in 9 genera For duck as a food see Duck (food; for other meanings see Duck (disambiguation. Cassowaries ( Genus Casuarius) are very large flightless Birds native to the Tropical forests of New Guinea and The domestic hen's egg has around 7500 pores. The chicken ( Gallus gallus, sometimes G gallus domesticus) is a domesticated Fowl which is traditionally believed to have descended from
Shape
Most bird eggs have an oval shape, with one end rounded and the other more pointy. In geometry an oval or ovoid (from Latin ovum, 'egg' is any Curve resembling an egg or an Ellipse. This shape results from the egg being forced through the oviduct. Oviduct is also another name for Fallopian tube In Oviparous Animals (those that lay eggs, the passage from the ovaries Muscles contract the oviduct behind the egg, pushing it forward. The egg's wall is still shapeable, and the pointy end develops at the back side. Cliff-nesting birds often have highly conical eggs. They are less likely to roll off, tending instead to roll around in a tight circle; this trait is likely to have arisen due to evolution via natural selection. In contrast, many hole-nesting birds have nearly spherical eggs.
Predation
Many animals feed on eggs. For example, principal predators of the Black Oystercatcher's eggs include raccoons, skunks, mink, river and sea otters, gulls, crows and foxes. The American Black Oystercatcher, Haematopus bachmani, also called Western Black Oystercatcher, is a conspicuous black bird found on the shoreline The raccoon ( Procyon lotor) (sometimes spelt as racoon) also known as the common raccoon, North American raccoon, northern raccoon Skunks (sometimes referred to as polecats) are Mammals best known for their ability to excrete a strong foul-smelling odor. There are two living species of " mink," the American Mink and the European Mink. Otters are semi- aquatic (or in one case aquatic) fish-eating Mammals The otter subfamily Lutrinae forms part of the family Gulls (often informally Seagulls) are birds in the family Laridae The true crows are large Passerine Birds that comprise the Genus Corvus in the family Corvidae. A fox is an Animal belonging to any one of about 27 Species (of which only 12 actually belong to the Vulpes genus or 'true foxes' of small The stoat (Mustela erminea) and long-tailed weasel (M. The Long-tailed Weasel ( Mustela frenata) is the most widely distributed Mustelid in the New World. frenata) steal ducks' eggs. Snakes of the genera Dasypeltis and Elachistodon specialize in eating eggs. Dasypeltis is a Genus of Colubrid Snakes It is one of only two taxonomic groups of snakes known to have adapted to feed exclusively Indian Egg-eating Snake ( Elachistodon westermanni) is a rare Species of Egg-eating snake found in Bangladesh, India, and
Brood parasitism occurs in birds when one species lays its eggs in the nest of another. Brood parasites are organisms that use the strategy of brood-parasitism, a kind of Kleptoparasitism found among Birds Fish or Insects In some cases, the host's eggs are removed or eaten by the female, or expelled by her chick. Brood parasites include the cowbirds and many Old World cuckoos. Cowbirds are Birds belonging to the genus Molothrus in the family Icteridae. The cuckoos are a family Cuculidae, of Near passerine Birds The order Cuculiformes, in addition to the cuckoos also includes the
Various bird eggs
 An average Whooping Crane egg is 102 mm long, and weighs 208 grams |
 Eggs in a nest |
 Eggs of hummingbird, hen, and ostrich |
 Senegal Parrot egg (on 1cm grid). The Whooping Crane ( Grus americana) the tallest North American bird is an Endangered crane species named for its whooping sound and call A bird that nests in tree holes. |
Fish eggs (Amniotic Egg)
The most common reproductive strategy for fish is known as oviparity, in which the female lays undeveloped eggs that are externally fertilized by a male. Fish are aquatic Vertebrate animals that are typically ectothermic (previously Cold-blooded) covered with scales, and equipped with two Oviparous animals are animals that lay eggs, with little or no other Embryonic development within the mother Typically large numbers of eggs are laid at one time (an adult female cod can produce 4–6 million eggs in one spawning) and the eggs are then left to develop without parental care. Cod is the common name for the Genus Gadus of Fish, belonging to the family Gadidae, and is also used in the common name of a variety When the larvae hatch from the egg, they often carry the remains of the yolk in a yolk sac which continues to nourish the larvae for a few days as they learn how to swim. Once the yolk is consumed, there is a critical point after which they must learn how to hunt and feed or they will die.
A few fish, notably the rays and most sharks use ovoviviparity in which the eggs are fertilized and develop internally. Batoidea is a Superorder of cartilaginous fish containing more than 500 described species in thirteen families Sharks ( Superorder Selachimorpha) are a type of Fish with a full cartilaginous Skeleton and a highly streamlined body Ovoviviparous Animals develop within eggs that remain within the mother's body up until they hatch or are about to hatch However the larvae still grow inside the egg consuming the egg's yolk and without any direct nourishment from the mother. The mother then gives birth to relatively mature young. In certain instances, the most physically-developed offspring will devour its smaller siblings for further nutrition while still within the mother's body. This is known as intrauterine cannibalism. Cannibalism is the act of one individual of a species consuming all or part of another individual of the same species as food
In certain rare scenarios, some fish such as the hammerhead shark and reef shark are viviparous, with the egg being fertilized and developed internally, but with the mother also providing direct nourishment. Hammerhead sharks of the Genus Sphyrna are members of the family Sphyrnidiae. A viviparous Animal is an animal employing vivipary: the embryo develops inside the body of the mother as opposed to outside in an egg ( Ovipary
Other eggs
Invertebrate eggs
Eggs are common among invertebrates, including insects, mollusks, and crustaceans. The Common Snapping Turtle ( Chelydra serpentina) is a large freshwater Turtle of the family Chelydridae Insects ( Class Insecta) are a major group of Arthropods and the most diverse group of Animals on the Earth with over a million described Molluscs are animals belonging to the phylum Mollusca. There are around 250000 extant Species within the phylum with an estimated 70000 Structure of crustaceans As Arthropods crustaceans have a stiff Exoskeleton, which must be shed to allow the animal to grow ( Ecdysis or molting
Fish and amphibian eggs
The eggs of fish and amphibians are jellylike. Fish are aquatic Vertebrate animals that are typically ectothermic (previously Cold-blooded) covered with scales, and equipped with two Prehistoric amphibian Amphibians (class Amphibia such as Frogs Toads Salamanders Newts Gymnophiona, Sirens and Fish eggs are fertilized externally, typically with the male inseminating the eggs after the female lays them. These eggs do not have a shell and would dry out in the air. Even air-breathing amphibians lay their eggs in water, or in protective foam as with the Coast foam-nest treefrog, Chiromantis xerampelina. UserPolbot. --> The Grey Foam-nest Treefrog or Southern Foam-nest Treefrog ( Chiromantis xerampelina
Amniote eggs and embryos
Like amphibians, amniotes are air-breathing vertebrates, but they have complex eggs or embryos, including an amniotic membrane. The amniotes are a group of Tetrapod Vertebrates that include the Synapsida ( Mammals and Mammal-like reptiles and Sauropsida Amniotes include reptiles, dinosaurs, birds, and mammals. Reptiles, or members of the class Reptilia are air-breathing Cold-blooded Vertebrates that have skin covered in scales as opposed to hair or feathers Birds ( class Aves) are bipedal endothermic ( Warm-blooded) Vertebrate animals that lay eggs. Mammals ( class Mammalia) are a class of Vertebrate Animals characterized by the presence of Sweat glands, including sweat glands
Reptile eggs are often rubbery and are always initially white. They are able to survive in the air. Often the sex of the developing embryo is determined by the temperature of the surroundings, with cooler temperatures favouring males. Not all reptiles lay eggs; some are viviparous ("live birth"). A viviparous Animal is an animal employing vivipary: the embryo develops inside the body of the mother as opposed to outside in an egg ( Ovipary
Dinosaurs laid eggs, some of which have been preserved as petrified fossils.
Among mammals, early extinct species laid eggs, as do platypuses and echidnas (spiny anteaters). The Platypus ( Ornithorhynchus anatinus) is a semi- aquatic Mammal endemic to eastern Australia, including Tasmania. Echidnas (ɨˈkɪdnə also known as spiny anteaters, are four extant Mammal species belonging to the Tachyglossidae family of the Platypuses and two genera of echidna are Australian monotremes. Echidnas (ɨˈkɪdnə also known as spiny anteaters, are four extant Mammal species belonging to the Tachyglossidae family of the Monotremes (from the Greek monos 'single' + trema 'hole' referring to the Cloaca) are Mammals that lay eggs ( Prototheria) instead Marsupial and placental mammals do not lay eggs, but their unborn young do have the complex tissues that identify amniotes. Marsupials are an Infraclass of Mammals characterized by a distinctive pouch (called the marsupium) in which females carry their young through See also Evolution of mammals Eutheria ("true beast" are a group of Mammals consisting of Placental mammals plus all extinct Mammals
 A baby tortoise emerges from its egg. Tortoises or land Turtles are land-dwelling Reptiles of the family of Testudinidae', order Testudines. |
 Insect eggs, in this case those of the Emperor Gum Moth, are often laid on the underside of leaves. The emperor gum moth, Opodiphthera eucalypti, is a species of Moth native to Australia, and can be easily found in all the states except for Tasmania |
 Fish eggs, such as these herring eggs are often transparent and fertilized after laying |
_01.jpg/120px-Skate_egg_case_(Raja_binoculata)_01.jpg) Skates (and sharks) have a uniquely shaped egg case called a mermaid's purse |
References
- Marine Biology notes from School of Life Sciences, Napier University. Herring are small Oily fish of the genus Clupea found in the shallow temperate waters of the North Atlantic, the Baltic Sea, the North Skates are cartilaginous fish belonging to the family Rajidae in the superorder Batoidea of rays Sharks ( Superorder Selachimorpha) are a type of Fish with a full cartilaginous Skeleton and a highly streamlined body Mermaid's purses (also known as Devil's Purses are the normally empty egg cases of Skates Sharks and rays.
- Speckles Make Bird Eggs Stronger, Study Finds John Pickrell, National Geographic News, 11 Oct 2005.
- Andrew Gosler, Yet even more ways to dress eggs in British Birds, vol 99 no 7, July 2006
See also
An egg is a round or oval body laid by the female of many animals consisting of an Ovum surrounded by layers of Membranes and an outer casing which acts to nourish An egg yolk is the part of an egg which serves as the Food source for the developing Embryo inside Albumen redirects here For other uses see Albumen (disambiguation. Trophic egg is an egg which is not laid for Reproduction but for Nutrition, often for offspring hatched from regular eggs.Dapyx Software network: MP3 Explorer | Ebook Manager | Zenithic