Chapter 26: Sponges and Cnidarians. 26-1 Introduction to the Animal Kingdom What makes animals...
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Transcript of Chapter 26: Sponges and Cnidarians. 26-1 Introduction to the Animal Kingdom What makes animals...
Chapter 26: Sponges and Cnidarians
26-1 Introduction to the Animal Kingdom
What makes animals different from the previous organisms we have covered so far this
year?
The Animal Kingdom• Multicellular
• Eukaryotic
• Heterotrophs
• Cells lack cell walls
• 95% are invertebrates
26-1 Introduction to the Animal Kingdom
26-1 Introduction to the Animal Kingdom
26-1 Introduction to the Animal Kingdom
What Animals Do to Survive
• Feeding
• Respiration
• Circulation
• Excretion
• Response
• Movement
• Reproduction
26-1 Introduction to the Animal Kingdom
1. Feeding
• Modes of ingestion of nutrients
Carnivores
Herbivores
Detrivores
26-1 Introduction to the Animal Kingdom
2. Respiration
• Taking in oxygen, releasing carbon dioxide
Lungs Gills Skin
26-1 Introduction to the Animal Kingdom
3. Circulation
• Movement of materials in the body
Heart Pump Diffusion
26-1 Introduction to the Animal Kingdom
4. Excretion
• Removal of nitrogen waste out of body to maintain homeostasis
Diffusion Kidney
26-1 Introduction to the Animal Kingdom
5. Response
• Responding to outside stimuli using nerve cells
26-1 Introduction to the Animal Kingdom
6. Movement
• Attached to a single spot or motile
26-1 Introduction to the Animal Kingdom
7. Reproduction
26-1 Introduction to the Animal Kingdom
Trends in Animal Evolution
Though there are differences in whether an animal has a backbone or not, there are some common trends:
1. Cell Specialization
2. Body Symmetry
3. Cephalization
4. Body Cavity Formation
26-1 Introduction to the Animal Kingdom
1. Cell Specialization• Animal cells have evolved to carry out
specific functions:
26-1 Introduction to the Animal Kingdom
1. Cell Specialization
• Reasons why cell specialization is important:
• Allows for animals to perform many different functions
• Causes a greater efficiency in survival
26-1 Introduction to the Animal Kingdom
Early Embryonic Development
• Animals that reproduce sexually begin life after fertilization as a zygote (fertilized egg)
• Zygote undergoes a series of divisions
• Blastula forms (simple ball of cells)
• Blastula fold in on itself forming blastopore
• Blastopore leads into a central tube
26-1 Introduction to the Animal Kingdom
Early Embryonic Development
26-1 Introduction to the Animal Kingdom
26-1 Introduction to the Animal Kingdom
Protostome Animals mouth forms from
blastopore (most invertebrates)
Deuterostome Animals anus forms from
blastopore (echinoderms and
vertebrates
Early Embryonic Development
26-1 Introduction to the Animal Kingdom
• Endoderm inner
• Mesoderm middle
• Ectoderm outer
Cells differentiate into 3 germ layers
Early Embryonic Development
26-1 Introduction to the Animal Kingdom
2. Body Symmetry
• Ability to divide a body into 2 equal halves
26-1 Introduction to the Animal Kingdom
2. Body Symmetry
• Planes of symmetry: Dorsovental Axis (Sagittal
Plane)• Cuts the body into right and left sides
26-1 Introduction to the Animal Kingdom
2. Body Symmetry
• Planes of symmetry: Transverse Axis
•Produces a “cross-section” of the body
• Divides the body into “Anterior” and “Posterior” regions
26-1 Introduction to the Animal Kingdom
2. Body Symmetry
• Regions of the body:
Anterior: Front
Posterior: Rear End
Ventral: Lower
Dorsal: Upper
26-1 Introduction to the Animal Kingdom
Trends of Evolution
There are two more characteristics that most animals share in addition to “Cell Specialization” and “Body Symmetry”
3. Cephalization
4. Body Cavity Formation
26-1 Introduction to the Animal Kingdom
3. Cephalization
Refers to the characteristic that more sense organs and nerve cells are located at the anterior part of the body than anywhere else
26-1 Introduction to the Animal Kingdom
3. Cephalization
Allows animals to respond quicker and in more complex ways to stimuli
26-1 Introduction to the Animal Kingdom
Body cavity is a fluid-filled space that contains the organs
4. Body Cavity Formation
26-1 Introduction to the Animal Kingdom
4. Body Cavity Formation
This allows space for internal organs to keep their shape and to grow properly
26-1 Introduction to the Animal Kingdom
Evolutionary Relationships26-1 Introduction to the Animal Kingdom
26-2 SPONGES
Sponges• Phylum Porifera
• Have tiny openings, or pores, all over their bodies
• Sessile: they live their entire life attached to a single spot
• They are animals. Why…?
26-2 Sponges
Sponges are Animals
• Multicellular
• Heterotrophic
• No cell walls
• Contain a few specialized cells
26-2 Sponges
Click Picture To Watch a 3 Minute Sponge From and Function Video
Form and Function in Sponges
• Have nothing resembling a mouth or gut
• Have no tissues or organ systems
• Simple functions are carried out by a few specialized cells
26-2 Sponges
Asymmetrical
• Have no front or back ends, no left and right sides
• A large, cylindrical water pump
• The body forms a wall around a large central cavity through which water flows continually
26-2 Sponges
26-2 Sponges
Specialized Cells
• Choanocytes – Specialized cells that use flagella to
move a steady current of water through the sponge
• Osculum – Water leaves through the large
hole at the top of the sponge
26-2 Sponges
Choanocytes
• Specialized cells that use flagella to move a steady current of water through the sponge
• Filters several thousand liters/day
26-2 Sponges
Osculum
• A large hole at the top of the sponge, through which water exits
• The movement of water provides a simple mechanism for feeding, respiration, circulation and excretion
26-2 Sponges
Specialized Cells• spicule
– is a spike-shaped structure made of chalklike calcium carbonate or glasslike silica
• archaeocytes – are specialized cells that move around within
the walls of the sponge and make spicules.
• spongin – network of flexible protein fibers that make
up the internal skeleton of a sponge.
26-2 Sponges
Simple Skeleton
• Spicule: a spike-shaped structure made of chalk-like calcium carbonate or glasslike silica in hard sponges
• Archaeocytes: specialized cells that make spicules
26-2 Sponges
26-2 Sponges
Sponge Feeding
• Filter feeders
• Sift microscopic food from the water
• Particles are engulfed by choanocytes that line the body cavity
26-2 Sponges
Click Picture To Watch a 5 Minute Sponge Filter Feeding Video
Respiration, Circulation, & Excretion
• Rely on the movement of water through their bodies to carry out body functions
• As water moves through the cavity:
• Oxygen dissolved in the water diffuses into the surrounding cells
• Carbon dioxide and other wastes, diffuse into the water and are carried away
26-2 Sponges
Response
• No nervous system
• Many sponges protect themselves by producing toxins that make them unpalatable or poisonous to potential predators
26-2 Sponges
Reproduction
• Sexually or asexually
• A single spore forms both eggs and sperm; usually at different times
26-2 Sponges
Click Picture To Watch A 2 Minute Sponge Reproduction Video
Sexual Reproduction
• Internal fertilization: Eggs are fertilized inside the sponge’s body
• Sperm are released from one sponge and carried by currents to the pores of another sponge
26-2 Sponges
Asexual Reproduction
26-2 Sponges
• Budding
• Gemmules: groups of archaeocytes surrounded by spicules
Ecology of Sponges
• Ideal habitats for marine animals such as snails, sea stars, sea cucumbers, and shrimp
• Mutually beneficial relationships with bacteria, algae and plant-like protists
– Many are green due to these organisms living in their tissues
26-2 Sponges
Ecology of Sponges
• Attached to the seafloor and may receive little sunlight
• Some have spicules that look like cross-shaped antennae
• Like a lens or magnifying glass, they focus and direct incoming sunlight
26-2 Sponges
26-3 CNIDARIANS
Cnidarians• Phylum Cnidaria
• Hydras, jellies, sea anemones, and corals
• Soft-bodied
• Carnivorous
• Stinging tentacles arranged in circles around their mouths
• Simplest animals to have body symmetry and specialized cells
26-3 Cnidarians
Cnidocytes
• Stinging cells that are located on their tentacles
• Used for defense and to capture prey
26-3 Cnidarians
Nematocyst
• A poison-filled, stinging structure that contains a tightly coiled dart
• Found within cnidocytes
26-3 Cnidarians
26-3 Cnidarians Click Picture To Watch a 2 Minute Feeding Anemone Video
26-3 Cnidarians Click Picture To Watch a 3 Minute Stinging Jellyfish Video
Form and Function in Cnidarians
• Only a few cells thick
• Simple body systems
• Most of their responses to the environment are carried out by specialized cells and tissues
26-3 Cnidarians
Radially Symmetrical
• Central mouth surrounded by numerous tentacles that extend outward from the body
• Life cycles includes a polyp and a medusa stage
26-3 Cnidarians
Body Plan
• Polyp: cylindrical body with arm-like tentacles; mouth points upward
• Medusa: motile, bell-shaped body; mouth on the bottom
26-3 Cnidarians
Epidermis
Mesoglea
Gastroderm
Mesoglea
Gastrovascular cavity
Mouth/anus
Tentacles
Tentacles
Mouth/anus
Gastrovascularcavity
Polyp
Medusa
Phylum Cnidarian26-3 Cnidarians
Feeding
• Polyps and medusas have a body wall that surrounds an internal space: the gastrovascular cavity
• Gastrovascular cavity: a digestive chamber with one opening
– Food enters and wastes leave the body
26-3 Cnidarians
Respiration, Circulation, & Excretion
• Following digestion, nutrients are usually transported throughout the body by diffusion
• Respire and eliminate wastes by diffusion through body walls
26-3 Cnidarians
Response• Specialized sensory cells are used to gather
information from the environment
• Nerve net: loosely organized network of nerve cells that together allow cnidarians to detect stimuli
– Distributed uniformly throughout the body in most species
– In some species it is concentrated around the mouth or in rings around the body
26-3 Cnidarians
26-3 Cnidarians
Response
• Statocysts: groups of sensory cells that help determine the direction of gravity
• Ocelli: eyespots made of cells that detect light
26-3 Cnidarians
Movement
• Hydrostatic skeleton: a layer of circular muscles and a layer of longitudinal muscles that enable cnidarians to move
26-3 Cnidarians
Reproduction: Sexually and Asexually
• Polyps can reproduce asexually by budding
• External sexual reproduction
– The sexes are separate-each individual is either male or female
– Both egg and sperm are released into the water
26-3 Cnidarians
26-3 Cnidarians
26-3 Cnidarians
26-3 Cnidarians
Groups of Cnidarians
• Jellies (formerly jellyfishes)
• Hydras and their relatives
• Sea anemones
• Corals
26-3 Cnidarians
26-3 Cnidarians
• Class Scyphozoa: “cup animal”– Jellyfish
26-3 Cnidarians
Groups of Cnidarians
• Spend most of their lives as medusa
• The polyp form is limited to a larva stage
Classes of Cnidarians Class Scyphozoa
26-3 Cnidarians
• The largest jellyfish ever found is 4 meters in diameter with tentacles more than 30 meters in length
• Most species are harmless, many can cause servere allergic reactions/even kill people
26-3 Cnidarians
Classes of Cnidarians Class Scyphozoa
26-3 Cnidarians
26-3 Cnidarians
• Class Hydrozoa: Hydras; Portuguese Man of War
26-3 Cnidarians
Groups of Cnidarians
• The polyps of most hydrozoans grow in branching colonies that sometimes extend more than a meter.
• Within a colony, the polyps are specialized to perform different functions.
• EX: One polyp forms a balloon-like float that keeps the entire colony afloat
• Portuguese Man of War
Classes of Cnidarians Class Hydrozoa
26-3 Cnidarians
• Most common in freshwater hydrozoan is a hydra
• Lack medusa stage (solitary polyp)• Reproduce sexually (producing eggs and
sperm in the body wall) and asexually (budding)
• a few species are hermaphroditic
Classes of Cnidarians Class Hydrozoa
26-3 Cnidarians
Click Picture To Watch a 2 Minute Hydra Budding Video
26-3 Cnidarians
• Class Anthozoa: “flower animal”– Sea Anemones and Corals
26-3 Cnidarians
Groups of Cnidarians
• Grow only as polyps / no medusa stage
• Central body that is surrounded by tentacles
• Many species are colonial (composed of many individual polyps)
Classes of Cnidarians Class Anthozoa
26-3 Cnidarians
• Corals and sea anemones reproduce sexually by producing free swimming larvae
• The free swimming larvae attach to rocks and then form polyps
• Also can reproduce by budding
Classes of Cnidarians Class Anthozoa
26-3 Cnidarians
26-3 Cnidarians
Classes of Cnidarians Class Anthozoa
• Forming Coral Reefs– Formed when hard coral from layers of
skeleton (CaCO3)
– Algae forms a sybiotic relationship with coral
26-3 Cnidarians Click Picture To Watch a 1 Minute Coral Budding Video
26-3 Cnidarians
Ecology of Corals• The worldwide distribution is determined by:
– Temperature
– Water depth
– Light intensity
• Many suffer from human activity• Coral bleaching has become common • Global warming may add to the problem
26-3 Cnidarians
Click Picture To Watch a 5 Minute Coral Spawn Video