BIS 2C Lecture Notes - Lecture 27: Cnidocyte, Diploblasty, Planula
27 Apr 2018
School
Department
Course
Ctenophores (Cone Jellies) - sister to all other animals not Porifera
Radial symmetry
•
Neither protostomes or deuterostomes
•
Diploblastic devo
•
Complete gut (differ from cnidarians)
•
Nervous system
•
Simple muscles
•
Feed on small plankton
Some eat other ctenophores
○
•
Cnidarian
Radial Symmetry: around oral end which has tentacles (open) and aboral end
•
Incomplete gut: single opening which serves as mouth and anus for two way digestion
•
Diploblastic: two layers separated by a mesoglea
Ectoderm (epidermis)
○
Endoderm ()
○
•
Two body forms
Polyp: tube shaped, sessile, oral end up (fewer sensory structure)
○
Medusa: motile with oral end facing down (more sensory structures)
Some cube jellies even have eyes with corneas, lens, retinas
§
○
Alternate between these
○
•
Have cnidocyte that is specialized with stinging or adhesive structure called a cnida
(pressurized coil)
Common type: nematocyst
○
•
Diffuse nervous system which is just nerve net
•
Muscle cells present but simple
•
Cnidarian Reproduction
Asexual Polyp
Free swimming medusa releases sperm and eggs
○
Zygote develops into ciliated larvae (planula) (gastrula occurs here after fertilization)
○
Larva settles and develops on substrate into polyp
○
Poly produce and release medusa asexually
○
•
Some cnidarians have no medusa stages
•
Cnidarian are sexually variable
•
Monecious vs Dioecious
Monoecious: single individual produces both sperm and eggs
•
Dioecious: sperm and eggs produced by diff individuals so different male/female
•
Examples
Sea jellies: dioecious
○
Corals and sea anemones: both
○
Cube jellies: dioecious (some copulate and hook up to release gametes in close
proximity)
○
•
Cnidarian Diet
All are carnivorous
•
Capture animals with tentacles and convey into gastrovascular cavity and extracellular
digestion occurs
•
Products of digestions are taken into nutritive cells to complete digestion intracellularly
•
Some have nutrition from symbionts
•
Cnidarian Diversity
12k species
•
Anthozoa: anemones, sea fans, coral
Coral - sessile and colonial with calcareous exoskeleton and intracellular
photosynthetic protists called zooxanthellae
○
Mutualism because zooxanthellae gives produces to photosynthesis and coral gives
metabolic wastes like N and P
○
•
Hydrozoa
•
Cubozoa
Cube jellies (sea wasp - toxic sting) - some cube jellies even have eyes with corneas,
lens, retinas
○
Common in Australia
○
•
Mutualism
Clownfish: have mucus that contains that deter firing of nematocysts
Benefits to fish: protection and nesting site food leftovers
○
Benefits to anemone: defense against predator and parasites, nutrients from clownfish
excrement
○
•
Over 2k nematocysts will penetrate one millimeter of human skin
•
Ctenophores and Cnidarians (27)
Wednesday, February 28, 2018
12:11 PM
Ctenophores (Cone Jellies) - sister to all other animals not Porifera
Radial symmetry
•
Neither protostomes or deuterostomes
•
Diploblastic devo
•
Complete gut (differ from cnidarians)
•
Nervous system
•
Simple muscles
•
Feed on small plankton
Some eat other ctenophores
○
•
Cnidarian
Radial Symmetry: around oral end which has tentacles (open) and aboral end
•
Incomplete gut: single opening which serves as mouth and anus for two way digestion
•
Diploblastic: two layers separated by a mesoglea
Ectoderm (epidermis)
○
Endoderm ()
○
•
Two body forms
Polyp: tube shaped, sessile, oral end up (fewer sensory structure)
○
Medusa: motile with oral end facing down (more sensory structures)
Some cube jellies even have eyes with corneas, lens, retinas
§
○
Alternate between these
○
•
Have cnidocyte that is specialized with stinging or adhesive structure called a cnida
(pressurized coil)
Common type: nematocyst
○
•
Diffuse nervous system which is just nerve net
•
Muscle cells present but simple
•
Cnidarian Reproduction
Asexual Polyp
Free swimming medusa releases sperm and eggs
○
Zygote develops into ciliated larvae (planula) (gastrula occurs here after fertilization)
○
Larva settles and develops on substrate into polyp
○
Poly produce and release medusa asexually
○
•
Some cnidarians have no medusa stages
•
Cnidarian are sexually variable
•
Monecious vs Dioecious
Monoecious: single individual produces both sperm and eggs
•
Dioecious: sperm and eggs produced by diff individuals so different male/female
•
Examples
Sea jellies: dioecious
○
Corals and sea anemones: both
○
Cube jellies: dioecious (some copulate and hook up to release gametes in close
proximity)
○
•
Cnidarian Diet
All are carnivorous
•
Capture animals with tentacles and convey into gastrovascular cavity and extracellular
digestion occurs
•
Products of digestions are taken into nutritive cells to complete digestion intracellularly
•
Some have nutrition from symbionts
•
Cnidarian Diversity
12k species
•
Anthozoa: anemones, sea fans, coral
Coral - sessile and colonial with calcareous exoskeleton and intracellular
photosynthetic protists called zooxanthellae
○
Mutualism because zooxanthellae gives produces to photosynthesis and coral gives
metabolic wastes like N and P
○
•
Hydrozoa
•
Cubozoa
Cube jellies (sea wasp - toxic sting) - some cube jellies even have eyes with corneas,
lens, retinas
○
Common in Australia
○
•
Mutualism
Clownfish: have mucus that contains that deter firing of nematocysts
Benefits to fish: protection and nesting site food leftovers
○
Benefits to anemone: defense against predator and parasites, nutrients from clownfish
excrement
○
•
Over 2k nematocysts will penetrate one millimeter of human skin
•
Ctenophores and Cnidarians (27)
Wednesday, February 28, 2018
12:11 PM
Document Summary
Ctenophores (cone jellies) - sister to all other animals not porifera. Radial symmetry: around oral end which has tentacles (open) and aboral end. Incomplete gut: single opening which serves as mouth and anus for two way digestion. Polyp: tube shaped, sessile, oral end up (fewer sensory structure) Medusa: motile with oral end facing down (more sensory structures) Some cube jellies even have eyes with corneas, lens, retinas. Have cnidocyte that is specialized with stinging or adhesive structure called a cnida (pressurized coil) Diffuse nervous system which is just nerve net. Zygote develops into ciliated larvae (planula) (gastrula occurs here after fertilization. Larva settles and develops on substrate into polyp ization) Larva settles and develops on substrate into polyp. Monoecious: single individual produces both sperm and eggs. Dioecious: sperm and eggs produced by diff individuals so different male/female. Cube jellies: dioecious (some copulate and hook up to release gametes in close proximity)
