1. Invertebrates I: Porifera, Cnidaria, Ctenophora, Platyhelminthes, Annelida

2. Tree of Life

3. Invertebrates - Background
Kingdom Animalia
97% of all animal species are invertebrates

4. Phylum Porifera (Sponges)
Simplest multicellular animals
Most are marine (~9000 species)
sessile (attached to substrate)
Diversity of shapes, sizes, colors, habitats

5. Cellular organization-complex aggregation of specialized cells
No true tissues/organs, cells largely independent from each other
No organs, movable parts, appendages
Thus, cells are plastic, can change from one type to another
Fig. 7.2

6. Shapes:
Tiny cups, broad branches, tall vases, encrusting round masses

7. Phylum Porifera (Sponges)-Gr. “pore-bearers”
Complex sponge
many chambers, oscula
Simple sponge
1 chamber, 1 osculum
Body Plan (Structure)- Asymmetrical
Ostia – water enters-pumped through these pores
Choanocytes – Collar cells; line chambers
Beat flagella to pump water through sponge
traps food particles
Osculum – water exits (driven by collar cells acting in synch)
Spongin – Elastic protein (spongy texture)
Spicules – Calcareous or siliceous structures, structural support, discourage predators
Amebocytes (wandering cells)– Secrete spongin and spicules, transport and store food particles, transform into other types of cells, repair

8. Phylum Porifera (Sponges)
Water/food IN
through ostia
Water-OUT
through osculum
Phylum Porifera (Sponges)
Feeding
Suspension feeders
Filter feeders (active suspension feeders)
Reproduction
Asexual
Sexual
Broadcast spawning

9. Fig. 7.3

10. II. Phylum Porifera 3 classes – defined by internal skeleton
Class Calcarea
CaCO3 spicules
Shallow tropical waters
Class Demospongiae
Bath sponge
Class Hexactinellida
Glass sponges, silica spicules
Deep waters

11. II. Phylum Porifera 3 classes – defined by internal skeleton
Class Calcarea
CaCO3 spicules
Shallow tropical waters (Leucosolenia, Scypha, Leucandra, Leucilla)
(drawing of Scypha slide)

12. II. Phylum: Porifera Class Hexactinellida
Glass sponges, silica spicules
Deep waters
(Euplectella specimen-Venus’s flower basket sponge, spicules slide)
Gr. Plecta = lace, this genus is known for lace-like skeleton fused glass spicules

13. II. Phylum: Porifera Class Demospongiae
Silica, spongin, or both, or lack skeleton
Bath sponge, rounded, spongin fibers
Encrusting forms, bright colors on rocks and corals
Boring types, through CaCO3
(Spongia specimen, note siliceous spiculation, internal budding)

14. Phylum Cnidaria 9000+ species Body Plan Sea anemones Corals Jellies
Body forms
Polyp - sessile
Medusa – free floating
Radial symmetry
Oral surface
Aboral surface

15. Fig. 7.5

16. III. Phylum Cnidaria Body Plan Cnidocytes (stinging cells)
Defense
Prey capture
Contain nematocysts (stinging capsule)
Simple nervous system
No true organs
Single opening
Mucus traps food

17. fluid Undischarged Discharged < 0.1 mm Trigger hair coiled thread

18. III. Phylum Cnidaria Class Hydrozoa Polyp forms Medusa forms colonial
Specialized polyps (zooids)
Gastrozooid - Feeding
Gonozooid – Reproduction
Dactylozooid – Defense (tentacles)
Medusa forms
Siphonophores – Colonial (e.g.- Portugese man of war)
Millepora species

19. III. Phylum Cnidaria, Class Hydrozoa
gastrozooid
gonozooid

20. Fig. 7.7

21. III. Phylum Cnidaria Class Scyphozoa Medusae large
E.g. – Cyanea capillata (Lion’s Mane)
Bell > 2 m
Tentacles 60+ m
Swim by contracting bell rhythmically, pulsating contraction
Stings *
Desmonema glaciale

22. Cyanea capillata

23. III. Phylum Cnidaria Class Anthozoa Polyp Passive suspension feeders
Solitary forms
Sea anemones
Colonial forms
Corals
Stony corals – branching and massive
- Some build reefs
Soft corals
Gorgonians
Sea pens
Sea pansies
Anthopleura xanthogrammica

24. Branching Corals
Doming Corals

25. Sea Pen
Soft Corals
Sea Pansy

26. Gorgonians (Sea Whips)

27. Gorgonians (Sea Fans)

28. III. Phylum Cnidaria Class Cubozoa Sea wasps, Box jellyfish
square bell
4 tentacles or bunches
Highly toxic

29. IV. Phylum Ctenophora (comb jellies)
Biradial symmetry
8 rows of ciliary combs (ctenes)
swimming
Carnivorous
Lack nematocysts
Capture prey with sticky colloblasts
May occur in swarms
Heavy predators

30. Pleurobrachia
Beroe

31. V. Phylum Platyhelminthes
Flatworms - Dorsoventrally flattened
Bilateral symmetry
Simplest organism with organs and organ systems
Digestive tract has 1 opening
No circulatory, respiratory, skeletal systems
Hermaphroditic

32. V. Phylum Platyhelminthes
A. Class Trematoda (Flukes)
Parasitic – Feed on tissues, blood, gut contents
Complex life cycles
Adults in vertebrate
Larvae in invertebrates
Vertebrate eats intermediate host
Body covered with cuticle resistant to digestion
Cestoda (Tapeworms)
Parasitic
Live in vertebrate intestines – (uncooked meat)
Head attaches w/4 suckers or hooks
Gutless – absorb nutrients through body wall
50 feet!! (sperm whales)

33. V. Phylum Platyhelminthes
C. Class Turbellaria
Mostly free-living carnivorous species
commensal animals inside invertebrates (oysters, crabs, etc.)
Most commonly seen (Why?)
Label ocelli=eyespots

35. VI. Phylum Annelida Segmented worms (1mm-3m) – flex/move more easily
Internally and externally, internal structures in tandem
Protective elastic cuticle
Body composed of repeated segments
Gut runs through all segments in body cavity (coelom-space around gut)
Coelom filled with fluid – hydrostatic skeleton
Coelom divided with septa-correspond to segments

36. Leech
Sabella pavonina
Nereis sp.
Lumbicus terrestris

37. VI. Phylum Annelida Class Polychaeta – tube worms, feather dusters
Body segments have pairs of parapodia
Parapodia for locomotion, feeding, gas exchange, protection
tipped with setae (bristles), often 4 pairs
Respiration: some with gills, exchange through body

38. VI. Phylum Annelida Class Polychaeta Larva = Trochophore
Band of cilia around body
Diverse lifestyles
Free-living predators
Burrowing
Tube building

39. Fig. 7.14

41. VI. Phylum Annelida Class Oligochaeta - earthworms
Few marine species
Benthic – mud and sand (deposit feeders)
No parapodia
Locomotion – expansion and contraction
Class Hirudinea (Leeches)
Freshwater mostly
One anterior/one posterior sucker to attach
Hirudin – anticoagulating chemical so blood does not clot
© 2004 Amanda Demopoulos