Clutch (eggs)

A clutch of eggs refers to all the eggs produced by birds, amphibians, or reptiles, often at a single time, particularly those laid in a nest.

In birds, destruction of a clutch by predators (or removal by humans, for example the California condor breeding program) results in double-clutching. The technique is used to double the production of a species' eggs, in the California condor case, specifically to increase population size. The act of putting one's hand in a nest to remove eggs is known as "dipping the clutch".

Size

Clutch size differs greatly between species, sometimes even within the same genus. It may also differ within the same species due to many factors including habitat, health, nutrition, predation pressures, and time of year.Clutch size variation can also reflect variation in optimal reproduction effort. Long-lived species tend to have smaller clutch sizes than short-lived species (see also r/K selection theory). The evolution of optimal clutch size is also driven by other factors, such as parent-offspring conflict.

Clutch

A clutch is a mechanical device that engages and disengages the power transmission, especially from driving shaft to driven shaft.

Clutches are used whenever the transmission of power or motion must be controlled either in amount or over time (e.g., electric screwdrivers limit how much torque is transmitted through use of a clutch; clutches control whether automobiles transmit engine power to the wheels).

In the simplest application, clutches connect and disconnect two rotating shafts (drive shafts or line shafts). In these devices, one shaft is typically attached to an engine or other power unit (the driving member) while the other shaft (the driven member) provides output power for work. While typically the motions involved are rotary, linear clutches are also possible.

In a torque-controlled drill, for instance, one shaft is driven by a motor and the other drives a drill chuck. The clutch connects the two shafts so they may be locked together and spin at the same speed (engaged), locked together but spinning at different speeds (slipping), or unlocked and spinning at different speeds (disengaged).

Egg

An egg is the organic vessel containing the zygote in which an animal embryo develops until it can survive on its own, at which point the animal hatches. An egg results from fertilization of an ovum. Most arthropods, vertebrates, and mollusks lay eggs, although some do not, such as scorpions and most mammals.

Reptile eggs, bird eggs, and monotreme eggs are laid out of water, and are surrounded by a protective shell, either flexible or inflexible. Eggs laid on land or in nests are usually kept within a favorable temperature range (warm) while the embryo grows. When the embryo is adequately developed it hatches, i.e. breaks out of the egg's shell. Some embryos have a temporary egg tooth with which to crack, pip, or break the eggshell or covering.

The largest recorded egg is from a whaleshark, and was 30 cm × 14 cm × 9 cm (11.8 in × 5.5 in × 3.5 in) in size; whale shark eggs normally hatch within the mother. At 1.5 kg (3.3 lb) and up to 17.8 cm × 14 cm (7.0 in × 5.5 in), the ostrich egg is the largest egg of any living bird, though the extinct elephant bird and some dinosaurs laid larger eggs. The bee hummingbird produces the smallest known bird egg, which weighs half of a gram (around 0.02 oz). 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.