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In this family of snails, the male phase ends in December, followed by an egg maturation phase, and ends with oviposition, the act of laying eggs during May of the following year. Phylogenetic evidence for this is present based on the overall condition of the gonads especially in the degree of development of the genital ducts. [7]
The mating of gastropods is a vast and varied topic, because the taxonomic class Gastropoda is very large and diverse, a group comprising sea snails and sea slugs, freshwater snails and land snails and slugs. Gastropods are second only to the class Insecta in terms of total number of species.
Following this, copulation occurs, with the one snail still mounted on the shell of the other, the two heads are brought together, and then twisted around each other's necks, enabling genital contact. This copulation then lasts up to four hours. An adult snail lays 25–35 eggs in a shallow pocket of soil and the eggs hatch after 30–40 days. [4]
Biomphalaria glabrata snails lay egg masses at rather a high rate (about 1 per day). [5] One snail can lay 14,000 eggs during its whole life span. [32] The periostracum of the embryonic shell (inside the egg) begin to grow in 48-hour old embryos. [34] Amorphous calcium carbonate appear in 54-60-hour old embryos. [34]
Shipworms, however, hatch directly as veligers, with the trochophore being an embryonic stage within the egg capsule. Many freshwater species go further, with the veliger also remaining within the egg capsule, and only hatching after metamorphosing into the adult form.
Egg capsules of Bithynia tentaculata with gastropods shortly before hatching. Bithynia tentaculata is dioecious (it has two separate sexes) and lays its eggs on rocks, wood and shells in organized aggregates arranged in double rows, in clumps of 1 to 77. Egg-laying occurs from May to July when water temperature is 20 °C (68 °F) or higher, and ...
A female mallard duck incubates her eggs. Egg incubation is the process by which an egg, of oviparous (egg-laying) animals, develops an embryo within the egg, after the egg's formation and ovipositional release. Egg incubation is done under favorable environmental conditions, possibly by brooding and hatching the egg.
The eggs hatch in about six days and the veliger larvae are planktonic for up to six months before settling on the shallow seabed at a shell-length of about 1 mm (0.04 in). [2] In eastern Canada these juvenile snails have been recorded at a density of 1500 per square meter. [3]