Some Happy Sea Creatures

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Some Happy Sea Creatures

• By Margaret Barnett
• Mary Jacobs
• Hanuel Jo

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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.
• -2 germ layers endoderm and ectoderm

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More Porifera

• Type of body development
• -The larvae
• flagellated
• swim freely for a short time
• After settling down and attaching to the ground,
  the larvae develop into young sponges.
• -All are sessile (live attached to something).

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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

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Porifera

• Reproduction
• sexually or asexually
• Asexual reproduction occurs by budding or by
  fragmentation.
• 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.

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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.
• Choanocytes filter small food items from the
  water such as individual bacteria.
• skeletal elements called spicules the cells that
  support the body

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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
• 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

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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

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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

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Ctenophores (a.k.a.comb-jellies)

• 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

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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.

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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

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