Which of these animal lays eggs

The old riddle, “Which came first, the chicken or the egg?” is relatively easy to answer as a question about the evolution of birth in animals. Egg laying almost certainly came before live birth; the armored fish that inhabited the oceans half a billion years ago and were ancestral to all land vertebrates seem to have laid eggs. But the rest of the story is far from straightforward. Over millennia of evolution, nature has come up with only two ways for a newborn animal to come into the world. Either its mother lays it in an egg, where it can continue to grow before hatching, or it stays inside its mother until emerging as a more fully formed squirming newborn. “We have this really fundamental split,” said Camilla Whittington, a biologist at the University of Sydney. Is there some primordial reason for this strict reproductive dichotomy between egg laying (oviparity) and live birth (viviparity)? When and why did live birth evolve? These are just some of the questions that new research — including studies of a remarkable lizard that can A Strategic Choice Early female animals laid eggs in the sense that they released their ova into the world, often thousands at a time. Sperm released by males then fertilized some of these eggs in a hit-or-miss fashion, and the resulting embryos took their chances on surviving in the hostile world until they hatched. Many creatures, particularly small, simple ones, still reproduce this way. But as animals became more complex, vertebrate speci...

What do you think of when you think of an egg? Do you think of the eggs that people typically eat, which come from The Even though many animals produce eggs, it’s interesting to think about the differences in these eggs. For example, which animal lays the largest egg? Read on to learn more about the animal that produces the largest egg in the world. 22,638 People Couldn't Ace This Quiz Think You Can? Take Our Brand New A-Z-Animals Birds Quiz The Largest Egg in the World The ostrich lays the largest egg in the world, with the average egg weighing three pounds and being six inches long. ©iStock.com/EcoPrint The largest egg in the world is laid by the However, although this egg is larger than any other animal’s egg, it’s actually very small in proportion to the mother Additionally, even though the ostrich has the largest egg of any animal, scientists found that these eggs are only about Considering that the yolk is the primary source of nutrition for the embryo, this could be why ostrich chicks are very After this, they become a little more independent, but they stay with the same flock until they are about seven months old. At this point, the How Are the Largest Eggs in the World Handled? Female ostriches lay their eggs in a communal nest, and the dominant female incubates them; when they hatch, the male takes care of them. ©Dominique de La Croix/Shutterstock.com In a group of All of the female Then, the dominant female incubates all of the eggs, her own and those of the oth...

We learn early on in school that what one of the distinguishing characteristics of mammals is that unlike birds, reptiles, and fish they bear live young. There are exceptions to every rule, some reptiles and fish bear live young, and some mammals lay eggs. Egg-laying mammals belong to a group called monotremes. Beside egg-laying, monotremes possess other traits that separate them from other mammals. They do not have teats to nurse their young. They instead excrete milk through pores that their young lap from. Their bodies maintained some reptilian traits such as a cloaca. Their legs are on the sides of their bodies, unlike other mammals, whose legs are positioned under their bodies. There are only 5 known species of monotremes still in existence. Keep reading for some fun facts about these fascinating animals. 5 mammals that lay eggs 1. Duck-billed Platypus image: • Scientific name: Ornithorhynchus anatinus • Where they’re found: Australia The platypus has a squat beaver-like body, with Duck-billed Platypus facts • Duck-billed platypus are the only • Platypus use electroreception to find food. They have around 40,000 electroreceptors in their bill and can detect weak electrical fields. When hunting they sweep their heads back and forth to locate their prey. • Platypus are knuckle walkers. To protect the webbing between their toes when walking on the land, they curl their toes under and walk on their knuckles. • They were originally thought to be a hoax. Since the duck-bill...

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