Squids and Starfish Kristina Moskalenko
Reproduction Squid Starfish • Reproduce like fish. • Release thousands of eggs into the water. • The male then fertilizes them. • Out of the eggs larvae will emerge which will then grow and develop into adults. • Sexually. • Has both sets of sexual organs. • Female and male. • Release gametes. Reproduce in water.
Embryo Development Squid Starfish • While it grows the space inside expands. • The shell is stretched away from the embryo. • The membrane is clearly visible. • One axis of the egg is twice as long as the other side. • The long axis if parallel to the egg shell. • Each starfish arm contains two gonads that release gametes. • Fertilization is usually external but in some species it’s internal. • The buoyant eggs and sperm are released into the water. • Most embryos of a starfish hatch at blastula stage. Both fertilize internally and externally depending on the species.
How the young develop Squid Starfish • Takes a week to develop from fertilization to hatching. • They float neither at the bottom or at the top, but in the middle of the vast environment. • Because they hatch fast it is hard to find an egg. • A hatching is called a paralarvae. • The difference between a hatchling and an adult is that a hatchling doesn’t have a proboscis. • Normal larvae go through cataclysmic metamorphosis which octopuses and squids don’t go through. • Most embryos hatch at blastula stage. • Which later develops a lateral pouch, archenteron. • Entrance to this is known as the blastopore and it will later develop into the anus. • A band of cilia develops on the exterior. • At this stage the larvae is known as bipinnaria. • The next stage in development is a brachiolaria larva and involves the growth of three short, additional arms. • Metamorphosis now takes place with a radical rearrangement of tissues.
How parents care for the young after birth squid Starfish • Both mom and dad take good care. • Die not long after reproduction. • The mother will care for the sac and will not eat anything until she mate. • The mother might die before or after the egg hatches leaving it free to swim. • Many species of starfish expel many eggs and sperms into the ocean, and fertilize them externally. • Then the larvae travels many miles by being swept away by the currents for two months. • As they develop, the tiny larvae swim in the sea and eat phytoplankton. • Starfish do not have brain therefore do not have the knowledge to care for the young.
Works cited: • http://wiki.answers.com/Q/How_does_a_starfish_care_for_it's_young?#slide=1 • http://wiki.answers.com/Q/How_can_an_octopus_take_care_of_its_young?#slide=1 • http://en.wikipedia.org/wiki/Starfish • http://wiki.answers.com/Q/How_do_squid_reproduce?#slide=1 • http://hermes.mbl.edu/publications/pub_archive/books/Brooks/