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Jet propulsion in squids and in scallops: these two groups of mollusks have very different ways of squeezing water through their bodies in order to power rapid movement through a fluid. (Dragonfly larvae in the aquatic stage also use an anal jet to propel them, and jellyfish have used jet propulsion for a very long time.)
The interior of a dinosaur egg can be studied using CAT scans or by gradually dissolving away the shell with acid. Sometimes the egg preserves the remains of the developing embryo inside. The oldest known dinosaur eggs and embryos are from Massospondylus, which lived during the Early Jurassic, about 190 million years ago. [2] [3]
Egg fossils are the fossilized remains of eggs laid by ancient animals. As evidence of the physiological processes of an animal, egg fossils are considered a type of trace fossil . Under rare circumstances a fossil egg may preserve the remains of the once- developing embryo inside, in which case it also contains body fossils .
The vessels either tow the nets through the sea or pump sea water onboard and then pass it through the net. [5] In addition to net tows, plankton is collected while the research vessel is moving using a Continuous Underway Fish Egg Sampler, or CUFES. Water is pumped aboard the vessel from 3 m depth at 640 liters/min.
This means anamniotes are almost always dependent on an aqueous (or at least very moist) environment for reproduction [2] and are thus restricted to spawning in or near water bodies. They are also highly sensitive to chemical and temperature variation in the surrounding water, and are also more vulnerable to egg predation and parasitism.
The surrounding egg white floats perfectly around the yolk, membrane intact. One of the divers was even able to make the egg 'dance' around by manipulating the current of the water around it.
Sauropterygians were a diverse group of aquatic reptiles adapted for flipper-based aquatic locomotion. This group included the plesiosaurs, nothosaurs, and placodonts. Mosasaurs were a group of large, aquatic squamates (relatives of modern-day lizards and snakes) which became the dominant marine predators towards the end of the Cretaceous period.
Whale shark eggs typically 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, [2]: 130 though the extinct elephant bird and some non-avian dinosaurs laid larger eggs.