SQUIDS AND STARFISHKristina Moskalenko

SQUID

Reproduce in water.

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.

STARFISH

REPRODUCTION

SQUID

Both fertilize internally and externally depending on the species.

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.

STARFISH

EMBRYO DEVELOPMENT

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.

SQUID

HOW THE YOUNG DEVELOP

SQUID 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.

STARFISH

HOW PARENTS CARE FOR THE YOUNG AFTER BIRTH

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/