Reproduction
27 questions tagged Reproduction — spanning every one of the seven Ws.
Why do seahorses have male pregnancies?
Male seahorses carry the developing young in a brood pouch, where they provide oxygen and nutrients until birth. This unusual role reversal helps improve survival of the embryos.
What are gametes?
Gametes are reproductive cells that carry one set of chromosomes. In humans, these are sperm and egg cells.
What is a pouch in marsupials?
A pouch is a skin fold that protects and supports the developing young of many marsupials. It helps keep the tiny newborn warm, safe, and able to nurse.
What is a placenta?
A placenta is an organ that develops during pregnancy and exchanges oxygen, nutrients, and waste between mother and fetus. It is central to the development of placental mammals.
What is brood parasitism in birds?
Brood parasitism is when one bird lays its eggs in another bird’s nest and leaves the host to raise the chicks. The best-known example is the cuckoo.
Why do mosquitoes need blood if they eat nectar too?
Only female mosquitoes need blood, because the protein and iron help them produce eggs. Males and females both drink nectar for energy.
Why do male seahorses get pregnant?
The female transfers eggs into the male’s brood pouch, and he carries the embryos until they are born. This rare role reversal is a hallmark of seahorse reproduction.
Why do turtles in the sea return to beaches to lay eggs?
Female sea turtles come ashore because their eggs need warm sand to develop safely. The beach environment gives the eggs the right temperature and protection from waterlogged conditions.
Why do some fish change sex during their lives?
Some species change sex because it can improve reproductive success depending on size, age, or social structure. In many reef fish, being male or female is more advantageous at different life stages.
Why do anglerfish males fuse to females in some species?
In some deep-sea anglerfish species, males attach permanently to females because mates are extremely hard to find in the deep ocean. The male becomes a sperm-producing partner that depends on the female for survival.
Why do fungi release so many spores at once?
Fungi release spores in huge numbers to increase the chance that some will land in the right place. Most spores never survive, so mass production is essential.
What is a brood patch in birds?
A brood patch is a featherless area on the belly that helps incubating birds transfer body heat to eggs. It is common in many nesting birds.
What is the amniotic egg?
An amniotic egg is a reptile or bird egg with extra membranes that protect the embryo and let it develop on land.
What is direct development in frogs?
Direct development is a frog life cycle in which the young hatch as miniature frogs instead of free-swimming tadpoles.
What is ovoviviparity in reptiles?
Ovoviviparity is a reproductive mode where eggs develop inside the parent and the young are born live.
What is pollination?
Pollination is the transfer of pollen from a plant's male part to its female part. It enables fertilization and seed production in many plants.
When did mammals first give birth to live young?
Live birth evolved very early in mammal history, by at least the Jurassic, over 160 million years ago.
Where are sperm cells produced?
Sperm cells are produced in the testes, specifically in the seminiferous tubules. They mature further in the epididymis.
Where are eggs or ova produced in the female body?
Egg cells are produced in the ovaries. They mature in follicles before ovulation.
Where do kiwi birds lay their eggs?
Kiwi birds lay their eggs in burrows, hollow logs, dense vegetation, or sheltered ground nests in New Zealand. Their eggs are exceptionally large for the bird’s body size.
Which bird has the largest eggs?
The ostrich lays the largest eggs of any living bird, and a single egg can weigh about 1.4 kilograms (3 pounds).
Which bird lays the smallest egg?
The bee hummingbird lays the smallest bird eggs, with eggs only about 1 centimeter long and weighing less than 1 gram.
Which bird has the longest incubation period?
The wandering albatross has one of the longest incubation periods among birds, with incubation lasting about 11 weeks.
Which shark can reproduce without a male?
Female hammerheads, blacktip sharks and some other sharks have been documented reproducing by parthenogenesis, though it is rare.
Whose work established that the mammalian placenta is not just a simple organ but a complex exchange system?
Keith L. Moore and later placental biologists helped define its anatomy and function. Placental studies expanded greatly in the 20th century as embryology advanced.
Whose research first explained how seahorses use male pregnancy?
Marine biologists in the 20th century established that male seahorses carry the developing embryos in a brood pouch. This is one of the most unusual reproductive systems in fish.
How do seahorses give birth to live young?
Male seahorses carry eggs in a brood pouch until the babies are ready to hatch. Then the male gives birth to fully formed miniature seahorses.