Transcript Some Happy Sea Creatures

Some Happy Sea Creatures
By Margaret Barnett
Mary Jacobs
Hanuel Jo
Porifera (a.k.a Sponges)
– No symmetry (asymmetrical)
– Body is multicellular
Number of germ layers and coelom:
 Cells and tissues surround a water filled
space
– is no true body cavity.
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-2 germ layers: endoderm and ectoderm
More Porifera
Type of body development:
 -The larvae
– flagellated
– swim freely for a short time
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After settling down and attaching to the
ground, the larvae develop into young
sponges.
 -All are sessile (live attached to something).
Porifera

instead of mouths, they have tiny pores in their
outer walls through which water flows.
 have few tissues but no organs and a nervous
system
 Did you know?
– Until 1765, sponges were thought to be plants because
they were so simple.
– Chemicals from sponges are being used to find a cure
for cancer and other diseases
Porifera
Reproduction:
 sexually or asexually
– Asexual reproduction occurs by budding or by
fragmentation.
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buds may remain attached to the parent or separate from it
each bud develops into a new individual.
Most sponges are hermaphroditic, the same
individual produces both eggs and sperm
– in some species the sexes are separate.
Specialized tissues of Porifera

Throughout the body of sponges, there are canals
through which water flows.
 The canals have openings to the outside, where the
water enters the sponge.
– These usually small pores are called ostia
– the pores are larger where the water leaves the sponge
system

These pores are called oscula(singular osculum).
– These canals are mostly lined with special flagellated
cells called choanocytes.
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Choanocytes filter small food items from the water such as
individual bacteria.
skeletal elements called spicules: the cells that
support the body
Cnidarians

Radial Symmetry
 Movement is coordinated by a decentralized
nerve net and simple receptors
– If they are free swimming they have more
complex nervous systems
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For example eyes, a gravity sensing organ, and an
inner ear similar to the ones in vertebrates
Have a sac-like body in two distinct layers
Cnidarians Continued

Gastro Vascular cavity- functions in both
digestion and gas exchange
 Two forms:
– Polyp: cylindrical, sessile, the mouth is facing
upward, does asexual reproduction
– Medusa: umbrella shaped, free swimming,
mouth facing downward, does sexual
reproduction
Cnidarians

The tentacles contain cnidocytes that are
cells which contain needle-like organelles
called cnidae
 Nematocysts are cnidae stinging capsules
– Found on the end of the tentacles of cnidarians
Ctenophores (a.k.a.comb-jellies)
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Ctenophore means “comb-bearer”
similar in appearance to cnidarian medusi
about 100 different species
1-10 cm in diameter
Most are spherical or ovoid (egg shaped)
Each ctenophore has eight rows of comb-like
plates composed of fused cilia
the largest animals to use cilia for locomotion
Portuguese Man-of-War
Colony

Not a jellyfish, it is a siphonophore
 Each man-of-war is composed of four types
separate polyps
– One polyp makes up the gas filled structure called the
pneumatophore. When inflated, the pneumatophore
resembles a Portuguese battleship floating on the
surface of the water. The chamber can be deflated to
allow the organism to submerge.
– The second polyp makes up the tentacles. Tentacles are
an average of 30 feet long but can grow to a length of
165 feet. The tentacles contain nematocytes that sting
and help capture prey.
– The third type of polyp, gastrozooids, surround the food
and digests it.
Coral Reef Formation

Coral reefs are composed of colonies of living
coral organisms and limestone skeletons of dead
coral
 Reefs occur only in clear tropical saltwater (64
degrees) at shallow depths that allow for
penetration of sunlight
 Coral depends on a symbiotic relationship with the
zooxanthellae, an algae that grows in
coral tissue