Porifera cnidaria and ctenophores
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Porifera, Cnidaria, and Ctenophores. By William Ruhe. Overview. Porifera- Sponges, Cnidaria- Sea anemones, coral, sea pens, Jellyfish, box jellyfish Ctenophora- Comb jellyfish. Porifera- Morphological Characteristics.

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Porifera- Sponges,

Cnidaria- Sea anemones, coral, sea pens,

Jellyfish, box jellyfish

Ctenophora- Comb jellyfish

Porifera morphological characteristics
Porifera- Morphological Characteristics

  • A sponges body is made up of two layers of cells separated by a substance made of mainly collagen called mesohyl.

  • The mesohyl cells also act as the organism’s endoskeleton.

  • Hollow bodies.

  • Inner surface covered in choanocytes- cells with whipping flagella that move water throughout the body.

  • Ostia- channels that go inside through mesohyl.

  • Pinacocytes- cells that act as plates, cover the mesohyl where the choanocytes are not.

Porifera morphological characteristics1
Porifera- Morphological Characteristics

  • Their mesohyl skeletons encrust hard surfaces for soft sponges.

  • Usually mesohyl is stiffened by spicules- provide structural support, made of silica, calcium or sponging.

  • Some sponges form large calcium carbonate exoskeletons.

  • They are not symmetrical.

  • Cells are not bound together.

Porifera body types
Porifera- Body types

  • Asconoid- Simplest shape, long tubular.

  • Syconoid- Increases pumping capacity making the diameter larger.

  • Leuconoid- Greatest diameter

Porifera body systems
Porifera- Body Systems

  • Sponges don’t have distinct circulatory, respiratory, digestive, or excretory systems.

  • Sponge cells absorb oxygen by diffusion as water flows through the body.

Porifera nutrition

  • Larger objects that they don’t fit through their ostia are externally engulfed and digested.

  • Food that is able to fit through the ostia are consumed by pinacocytes which stick out of the walls of the ostia.

  • Bacteria sized particles get digested by the choancytes.

  • Their waste leaves through their oscula.

Porifera reproduction
Porifera- Reproduction

  • Asexual- They use the method of budding- smaller pieces of sponge grow off of the larger sponge and get carried off with the currents.

  • Sexual- Most sponges are hermaphroditic, they have functions of both sexes. They have no reproductive organs.

  • Sperm are produced by the choanocytes, eggs are formed by archeocytes- cells in the sponge that can change into any type of cell.

  • Sperm are usually expelled out of the osculum to find another sponge of its species.

Porifera examples
Porifera- Examples

  • Spongia officinalis or the bath sponge.

  • This sponge is used commercially.

  • Turns yellow when dried, grey when alive.

  • Is hermaphroditic.

  • Found in the Mediterranean Sea.

Cnidaria morphological characteristics
Cnidaria- Morphological Characteristics

  • Four main groups: Anthozoa (sea anemones, coral, sea pens), Syphozoa (jellyfish), Cuboza (box jellyfish), Hydroza.

  • Either swimming medusae or sessile polyps.

  • Radially symmetrical

  • They have no heads so their ends are called oral and aboral, mouth and anus.

  • Most have tentacles around their edges

  • Medusae swim by propelling themselves with jets of water

Cnidaria morphological structures
Cnidaria- Morphological Structures

  • The only supporting structure in the Medusae is mesoglea- a jelly like substance that is between two epithelial layers. A basic type of tissue.

  • Sea anemones fill up with water act as a skeleton in a cavity when they are not feeding.

  • Sea pens harden their mesoglea with calcium carbonate spicules.

  • Corals make calcium carbonate exoskeletons

Cnideria morphological structures
Cnideria- Morphological Structures

  • Cnideria are diploblastic- two main cell layers, form epithelia. One cell thick.

  • Mesoglea separates the layers.

  • Layer on the outside- ectoderm has: cnidocytes, nerve cells that send messages to the motor nerve cells between bases of muscle cells.

Cnideria cnidocytes
Cnideria- Cnidocytes

  • Cnidocytes are like Harpoons

  • Three types: nematocyst- inject venom

  • Spirocysts – meant to entangle victim

  • Ptychocysts- build protectoral tube, found on tube anemones

Cnideria senses
Cnideria- Senses

  • They have no brains or central nervous system.

  • They have sensory neurons to provoke stimulus.

  • Most have simple eyes to tell which direction light is coming from.

  • Box jellies have true eyes that can sense light and can detect solid colored objects.

  • Respiration- cell layers absorb oxygen and expel carbon dioxide

  • Others with the central cavity replace stale water flushing out unused nutrients.

Cnideria nutrition
Cnideria- Nutrition

  • Predation- absorb organic nutrients

  • Filter food out of the water

  • Some depend completely on their endosymbiontants- algae that works with coral and other sessile cnideria to get nutrients

  • Predators use their cnidocytes to disable or entangle their prey. They also inject digestive enzymes into their prey and they push the animal into their digestive cavity where it is made into an absorbable liquid.

Cnideria reproduction
Cnideria- Reproduction

Life cycle of jellyfish

Cnideria reproduction1
Cnideria- reproduction

  • Sessile organisms send out their sperm hoping it reaches an egg.

  • The fertile egg becomes a hollow sphere/blastula which progresses into a digestive cavity through gastrulation.

  • Asexual- This is based on regeneration. If certain parts of the organism are cut off then the part can regenerate to make a whole.

Cnideria example
Cnideria- Example

  • Physalia physalis or otherwise know as the Portuguese Man of War.

  • Tentacles are usually 10 meters long.

  • They are always “fishing” with their tentacles.

  • No means of propulsion, pushed by currents and wind

  • Usually found in warm tropical waters.

Ctenophores morphological characteristics
Ctenophores- Morphological Characteristics

  • Swim by their cilia

  • Body made of mesoglea between epithelia bound by inter cell connection. Two layers instead of one

  • Outer layer of skin is covered in mucus to protect it, colloblasts on their tentacles to catch prey.

  • The inside layer has the nerve net instead of a brain, and cells acting as muscles

  • There is an inner cavity that is like a stomach and there is a canal system on the inside.

Ctenophores types

  • Cydippids- Round shape

  • Lobates- Have two lobes

  • Beroids- Large mouth, no feeding


Ctenophores morphological characteristics1
Ctenophores- Morphological Characteristics

  • Almost radially symmetrical

Ctenophores respiration
Ctenophores- Respiration

  • Water flows through its body, so it absorbs oxygen from the water that passes through it.

Ctenophores nutrition
Ctenophores- Nutrition

  • Food is put into the throat and digested by enzymes to make it digestible.

  • Nutrients are dispersed throughout the organism, absorbed by nutritive cells.

  • Most waste is regurgitated.

Ctenophores reproduction
Ctenophores- Reproduction

  • Almost all are hermaphroditic. Except in the genus ocryoposis where two species have single sex individuals.

  • Reproductive organs are located underneath the combs in the canals.

  • Eggs and sperm are released through pores in the skin.

  • However platyctenids have internal fertilization.

  • Juveniles resemble mini adults

  • They produce eggs and sperm as long as they have enough food.

Ctenophores bioluminescent
Ctenophores- Bioluminescent

  • Most of these creatures are bioluminescent.

  • Photocytes are activated which are photo proteins in cells.

  • Normally under the combs.

Ctenophores example
Ctenophores- Example

  • Cestum veneris or the Venus Girdle.

  • Looks like transparent ribbon.

  • Found in subtropical waters, open water.

Thank you

Thank You!

Very much!