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The eggs have an average diameter of 1 millimetre (0.039 in). The eggs are generally surrounded by the extraembryonic membranes but do not develop a shell, hard or soft, around these membranes. Some fish have thick, leathery coats, especially if they must withstand physical force or desiccation. These type of eggs can also be very small and ...
The eggs have an average diameter of 1 millimetre (0.039 in). The eggs are generally surrounded by the extraembryonic membranes but do not develop a shell, hard or soft, around these membranes. Some fish have thick, leathery coats, especially if they must withstand physical force or desiccation. These type of eggs can also be very small and ...
Females are larger than males, and Pacific swordfish reach a greater size than northwest Atlantic and Mediterranean swordfish. [6] They reach maturity at 4–5 years of age and the maximum age is believed to be at least 9 years. [6] The oldest swordfish found in a recent study were a 16-year-old female and 12-year-old male.
Kleptogenesis is a sexually parasitic form of reproduction in unisexual organisms, that is often associated with species that are also capable of gynogenetic reproduction. [8] In this reproductive mode unisexual females mate with sympatric males of related species, and genetic material in the paternal line recombines with the maternal DNA and ...
Various species of sea turtles bury their eggs on beaches under a layer of sand that provides both protection from predators and a constant temperature for the nest. Snakes may lay eggs in communal burrows, where a large number of adults combine to keep the eggs warm. Some species coil their torsos around the eggs to provide heat for incubation.
Adult swordfish have no teeth, and other billfish have only small file-like teeth. They swallow their catch whole, head-first. Billfish do not normally spear with their bills, though occasionally a marlin will flip a fish into the air and bayonet it. Given the speed and power of these fish, when they do spear things the results can be dramatic.
Batoids reproduce in a number of ways. As is characteristic of elasmobranchs, batoids undergo internal fertilization . Internal fertilization is advantageous to batoids as it conserves sperm, does not expose eggs to consumption by predators, and ensures that all the energy involved in reproduction is retained and not lost to the environment. [ 6 ]
Fish migrations involve movements of schools of fish on a scale and duration larger than those arising during normal daily activities. [1] Some particular types of migration are anadromous , in which adult fish live in the sea and migrate into fresh water to spawn ; and catadromous , in which adult fish live in fresh water and migrate into salt ...