Download - Invertebrate Diversity I Porifera, Cnidaria, Ctenophora, Platyhelminthes, Rotifera, Nematoda
Invertebrate Diversity IInvertebrate Diversity I
Porifera, Cnidaria, Ctenophora, Porifera, Cnidaria, Ctenophora, Platyhelminthes, Rotifera, Platyhelminthes, Rotifera,
NematodaNematoda
Kingdom Animalia• Heterotrophic ingesters• Multicellular
– “higher” groups have tissues – tissues arranged into organs in some groups
• No cell walls – flexible• Nervous tissue & Muscle tissue• No alternation of generations• Common early embryological development
2 Sub-kingdoms in Animalia
• Parazoa:– no symmetry
– no true tissues or organs
– 1 phylum: Porifera
• Eumetazoa:
– all symmetrical• radial or bilateral
– almost all have tissues
– all other animal phyla (~35 phyla)
Bases for traditional invertebrate taxonomy
1 Tissue specialization– Aggregates– Diploblastic – 2 germ layers– Triploblastic – 3 germ layers
Choanoflagellate Colony (Protist)
Bases for traditional invertebrate taxonomy
2 Body symmetry
None Radial Bilateral
Bases for traditional invertebrate taxonomy
3 Body Cavity
Bases for traditional invertebrate taxonomy
4 Early embryology
Cleavage
Coelom formation
Fate of blastopore
radial, indeterminate
enterocoelous
deuterostome
spiral, determinate
schizocoelous
protostomemouth anus
Two alternative family trees
morphological, developmental
Biochemical, molecular
Vertebrates vs. Invertebrates
• Invertebrates– “animals without backbones”
– 35.001 modern animal phyla
– origin of all modern phyla in Cambrian Explosion (~540mya)
• Vertebrates– “animals with backbones”
– one diverse subphylum of Ph. Chordata
– staggered evolution of vertebrate classes
Q1: Which of the following is NOT a common feature of the eumetazoan animals
1) cell walls
2) multicellular
3) heterotrophic
4) tissues
Q2: Which of the following is NOT a basis for traditional animal taxonomy
1) tissue specialization/number of germ layers
2) body symmetry
3) molecular similarities
4) early embryology
Ph. Porifera: the sponges
Anatomy of a Sponge
Spicules
Classes of Poriferans
• Calcarea – small, calcium spicules• Demospongae – larger, silica spicules
– the includes the bath sponges and flower baskets
• Hexactinellidae – hexagonal spicule array
– the “glass sponges”
Some poriferans . . .
Ph. Cnidariaformerly Colenterata (bag animals)
• true tissues - diploblastic (2 layers)
• no organs
• radially symmetric
• gastrovascular cavity with single opening
• cnidocytes, nematocysts, and tentacles
• 2 main body forms: polyp & medusa
Polyp -sessile, asexual
Medusa - motile, sexual
Cnidocytes: stinging cells
Classes of Cnidarians:
• Cl. Hydrozoa: hydroids (dominant polyp stage)
• Cl. Scyphozoa: true jellyfish
(dominant medusa stage)
• Cl. Anthozoa: sea anemones, corals (no medusa stage)
Class Hydrozoa
• The polypoid body form dominates
• Hydra
• Portuguese man o’ war
Man o’ war
A colonial hydroid!
Cl Scyphozoa: jellyfish
Cl Anthozoa -- anemone
Class Anthozoa:
Coral
Coral Polyps
Ph. Ctenophora: comb jellies
• 8 rows of ciliary plates
• digestive tube – 2 openings
• colloblasts (adhesive structures on tentacles)
Retractable tentacles!
Comb jelly
Ctenophore
Comb Jelly (“Sea gooseberry”)
Q3: Phylum Cnidaria is named for the characteristic
1) bag-like structure
2) medusa and polyp life stages
3) two germ layers
4) stinging cells
Q4: True jellyfish belong to the class
1) Hydrozoa
2) Scyphozoa
3) Anthozoa
4) Ctenophora
Ph. Platyhelminthes: flatworms
• Bilaterally symmetric• 3 tissue layers; organs• no body cavity: are acoelomates• dorsoventrally flattened (thus the name . . . )• primitive cephalization (but not in Class
Cestoidea)• blind-ended gut (also not in Cl. Cestoidea)• hermaphroditic (mostly)
4 classes of flatworms:
• Cl .Turbellaria: free-living flatworms, e.g., Planaria
• Cls. Trematoda & Monogenea: flukes
• Cl. Cestoidea: tapeworms
Planaria
Class Trematoda: flukes(digenetic – intermediate and definitive hosts)
Life Cycle of the
Blood Fluke(Schistosoma)
Political Cycle of the
Blood Fluke(Schistosoma
mansoni)
&
(or, what do politicians and parasites have in common?)
Class Cestoidea: tapeworms
Tapeworm encysted in muscle
Q5: Cestodes (tapeworms) differ from the other flatworms in that they
1) lack digestive organs
2) lack a cephalized nervous system
3) have a segmented body plan
4) all of the above
Ph. Rotifera: the rotifers
• Pseudocoelomates
• Mostly freshwater, but also on moss, lichens
• very small! But have complete digestive tract
• have a “crown of cilia” that draws food in toward their jaws
Rotifers
Rotifer
Ph. Acanthocephala – spiny-headed worms:
• barbed proboscis
• rudimentary gut
• intestinal parasites
• genomics suggests they are giant, modified rotifers
Ph. Nematoda:
• Unsegmented roundworms• pseudocoelomates• hydrostatic skeleton• many are animal parasites, e.g.,
pinworms, hook worms, Trichinella, Ascaris
• many are plant parasites
Nematode
Trichinella
Filariasis (Elephantiasis)
Microfilarial nematodesTransfer via mosquitoes
Adults live in blood stream & large lymphatic vesselsLarvae infest peripheral lymphatic capillaries - crepuscular
Body’s reaction is overgrowth of connective tissue
Q6: Pseudocoelomate phyla include the
1) Protista and Porifera
2) Cnidaria and Ctenophora
3) Platyhelminthyes and Chordata
4) Rotifera and Nematoda
Q7: All of the eumetazoan invertebrates we have discussed so far are
1) acoelomates
2) protostomes
3) segmented
4) secretly vertebrates