Invertebrates 1 Invertebrates 1 Introduction, Porifera, Introduction, Porifera, Cnidaria Cnidaria
Dec 21, 2015
Invertebrates 1Invertebrates 1
Introduction, Porifera, CnidariaIntroduction, Porifera, Cnidaria
Lecture outlineLecture outline
1.1. Overview: Invertebrate lecturesOverview: Invertebrate lectures2.2. What is an animal?What is an animal?3.3. Introduction to major phyla in Introduction to major phyla in
Kingdom AnimaliaKingdom Animalia4.4. Basic phylogeny of Kingdom Basic phylogeny of Kingdom
AnimaliaAnimalia5.5. Phylum PoriferaPhylum Porifera6.6. Phylum CnidariaPhylum Cnidaria
1. Overview of Invertebrate 1. Overview of Invertebrate portion of courseportion of course
Evolutionary relationshipsEvolutionary relationships Body planBody plan
How animal meets its basic needsHow animal meets its basic needs Relationship of structure and functionRelationship of structure and function
Selected aspects of life-history and Selected aspects of life-history and ecologyecology
2. What is an animal?2. What is an animal? EukaryoticEukaryotic Multicellular: Multiple cell Multicellular: Multiple cell typestypes (Not just many (Not just many
cells)cells) HeterotrophicHeterotrophic No cell wallNo cell wall Characteristics of early development (unique!)Characteristics of early development (unique!)
Blastula and gastrula stages unique to animalsBlastula and gastrula stages unique to animals Sponges, have precursors to these stagesSponges, have precursors to these stages
Phylum Porifera: Phylum Porifera: spongessponges
Phylum Cnidaria: Phylum Cnidaria: Have CnidocytesHave Cnidocytes
Phylum Ctenophora:Phylum Ctenophora:The comb jelliesThe comb jellies
Phylum Platyhelminthes:Phylum Platyhelminthes:The flatwormsThe flatworms
Phylum Nematoda:Phylum Nematoda:The roundwormsThe roundworms
Phylum Annelida:Phylum Annelida:The segmented wormsThe segmented worms
Phylum Mollusca:Phylum Mollusca:The “soft-bodied” The “soft-bodied”
animalsanimals
Phylum Arthropoda:Phylum Arthropoda:Jointed appendagesJointed appendages
Phylum Echinodermata:Phylum Echinodermata:Spiny-skinnedSpiny-skinned
Phylum Chordata:Phylum Chordata:Animals with notochordsAnimals with notochords
4. Phylogenetic overview4. Phylogenetic overview Presumed to be monophyleticPresumed to be monophyletic
Hypothesis assumes all animals evolve from a Hypothesis assumes all animals evolve from a single common ancestorsingle common ancestor
That ancestor thought to be a sponge-like protist That ancestor thought to be a sponge-like protist called a called a choanoflagellatechoanoflagellate
Modern choanoflagellateModern choanoflagellate Found in aquatic habitatsFound in aquatic habitats
Some propose Some propose polyphyletic originspolyphyletic origins
Cite Cambrian explosionCite Cambrian explosion
Phylogenetic overview Phylogenetic overview (“traditional”)(“traditional”)
Multicellularity separates the Multicellularity separates the ancestral protists from all ancestral protists from all
animalsanimals
MulticellularityMulticellularity
Different Different typestypes of cells! of cells!
Development of two true Development of two true tissue layerstissue layers
Separates Phylum Porifera from all Separates Phylum Porifera from all othersothers Sponges All other groups (2-3 tissues)Sponges All other groups (2-3 tissues)
Development of a third Development of a third germ layer and bilateral germ layer and bilateral
symmetrysymmetry Cnidarians, Ctenophores All others Cnidarians, Ctenophores All others Radial symmetry, 2 layers Bilateral symmetry, 3 layers Radial symmetry, 2 layers Bilateral symmetry, 3 layers
(Porifera)(Porifera)
Further developments Further developments (briefly)(briefly)
Body cavitiesBody cavities
AcoelomateAcoelomate PseudocoelomatesPseudocoelomates CoelomatesCoelomates
Further developments Further developments (briefly)(briefly)
5. Phylum Porifera: The 5. Phylum Porifera: The spongessponges
Evolutionary Evolutionary relationshipsrelationships
Simplest multicellular animals Simplest multicellular animals Main cell type, choanocyte, resembles Main cell type, choanocyte, resembles
choanoflagellate cellchoanoflagellate cell Considered "multicellular" rather than Considered "multicellular" rather than
colonial, because there are different cell colonial, because there are different cell types.types.
Not much, if any cooperation between cellsNot much, if any cooperation between cells No real "tissues", no "systems" of any type (no No real "tissues", no "systems" of any type (no
nervous system, circulatory system, etc.)nervous system, circulatory system, etc.)
Sponge structureSponge structure
Review key parts…Review key parts…
Water movement and Water movement and feedingfeeding
Role of flagellumRole of flagellum Role of collarRole of collar Movement of Movement of
particlesparticles PhagocytosisPhagocytosis
ProtectionProtection
Sponges are sessile… Sponges are sessile… Toxins/warning coloration (this is why Toxins/warning coloration (this is why
many sponges are brightly colored)many sponges are brightly colored) Painful or sharp covering (spicules)Painful or sharp covering (spicules) Regenerative abilityRegenerative ability Camouflage (if not toxic)Camouflage (if not toxic) Bore into shells. Bore into shells. NOTE: Nudibranch predators co-opt NOTE: Nudibranch predators co-opt
sponge defenses (toxins, spicules)sponge defenses (toxins, spicules)
Phylum CnidariaPhylum Cnidaria
Evolutionary Evolutionary relationshipsrelationships
Diverge from the Porifera in the Diverge from the Porifera in the following ways:following ways:
DiploblastiDiploblastic: two true tissue layers c: two true tissue layers Ectoderm and endodermEctoderm and endoderm No mesodermNo mesoderm
RadiataRadiata: One of two phyla to exhibit radial : One of two phyla to exhibit radial symmetrysymmetry
Where Cnidarians fit in…Where Cnidarians fit in…
Cnidarians, Ctenophores All others Cnidarians, Ctenophores All others Radial symmetry, 2 layers Bilateral symmetry, 3 layers Radial symmetry, 2 layers Bilateral symmetry, 3 layers
(Porifera)(Porifera)
Body organizationBody organization Polyps and medusaePolyps and medusae
Key featuresKey features
Polyps and medusaePolyps and medusae Tissue layersTissue layers
Ectoderm, gastroderm (=endoderm)Ectoderm, gastroderm (=endoderm) MesogliaMesoglia
Secreted from the tissue layersSecreted from the tissue layers Gastrovascular cavityGastrovascular cavity
FunctionsFunctions Not a true body cavity!Not a true body cavity!
Nervous system: nerve netNervous system: nerve net No other major body systemsNo other major body systems
Tentacles with cnidocytes (stinging cells)Tentacles with cnidocytes (stinging cells)
Nervous system featuresNervous system features
True neurons Conduction can be unidirectional or
bidirectional along neurons Nerve net with no direct pathways Have simple sensory organs
Cnidocytes/nematocystsCnidocytes/nematocystsHow do they work?How do they work?
Life-history strategiesLife-history strategies