second-largest phylum in number of species- over 100,000 described
DESCRIPTION
Phylum Mollusca. Second-largest phylum in number of species- over 100,000 described. Ecologically widespread- marine, freshwater, terrestrial (gastropods very successful on land) Variety of body plans (therefore, many classes within the phylum) - PowerPoint PPT PresentationTRANSCRIPT
![Page 1: Second-largest phylum in number of species- over 100,000 described](https://reader033.vdocument.in/reader033/viewer/2022051401/56812d54550346895d925af1/html5/thumbnails/1.jpg)
• Second-largest phylum in number of species- over 100,000 described.
• Ecologically widespread- marine, freshwater, terrestrial (gastropods very successful on land)
• Variety of body plans (therefore, many classes within the phylum)
• Variety in body size- from ~1 mm to ~18 m (60 feet). 80% are under 5 cm, but many are large and therefore significant as food for man.
Phylum Mollusca
![Page 2: Second-largest phylum in number of species- over 100,000 described](https://reader033.vdocument.in/reader033/viewer/2022051401/56812d54550346895d925af1/html5/thumbnails/2.jpg)
Extant Molluscan classes
Monoplacophora
Aplacophora
Scaphopoda (tusk shells)
Cephalopoda (octopus, squid,nautilus)
Gastropoda (snails)
Bivalvia (clams, mussels)
Polyplacophora (chitons)
![Page 3: Second-largest phylum in number of species- over 100,000 described](https://reader033.vdocument.in/reader033/viewer/2022051401/56812d54550346895d925af1/html5/thumbnails/3.jpg)
![Page 4: Second-largest phylum in number of species- over 100,000 described](https://reader033.vdocument.in/reader033/viewer/2022051401/56812d54550346895d925af1/html5/thumbnails/4.jpg)
Mollusk characteristics
• Ciliated body surface
• Calcareous shell- composed of three primary layers- outer periostracum, middle prismatic layer (columnar crystals of calcite) and inner nacre (flat crystals of calcite)
• Mantle- dorsal surface of body wall, modified to secrete shell
![Page 5: Second-largest phylum in number of species- over 100,000 described](https://reader033.vdocument.in/reader033/viewer/2022051401/56812d54550346895d925af1/html5/thumbnails/5.jpg)
More mollusk characteristics
• Radula- a rasping “tongue” with chitin teeth, sometimes also chitinous jaws
• Ctenidia- ciliated gills for respiratory gas exchange, usually located in a mantle cavity
• Open circulatory system (hemocoel)- coelom is reduced
![Page 6: Second-largest phylum in number of species- over 100,000 described](https://reader033.vdocument.in/reader033/viewer/2022051401/56812d54550346895d925af1/html5/thumbnails/6.jpg)
• ~800 species, all marine, many intertidal
• Shell is distinctive- 8 overlapping plates imbedded partly or entirely in tough “girdle”.
• Mantle space extends around perimeter of animal (not just posterior).
• Ctenidia are lateral and multiple.
• Very conservative class. Fossils date to mid/late Cambrian (500 my).
Class Polyplacophora (chitons)
![Page 7: Second-largest phylum in number of species- over 100,000 described](https://reader033.vdocument.in/reader033/viewer/2022051401/56812d54550346895d925af1/html5/thumbnails/7.jpg)
![Page 8: Second-largest phylum in number of species- over 100,000 described](https://reader033.vdocument.in/reader033/viewer/2022051401/56812d54550346895d925af1/html5/thumbnails/8.jpg)
A collection of chitons
![Page 9: Second-largest phylum in number of species- over 100,000 described](https://reader033.vdocument.in/reader033/viewer/2022051401/56812d54550346895d925af1/html5/thumbnails/9.jpg)
![Page 10: Second-largest phylum in number of species- over 100,000 described](https://reader033.vdocument.in/reader033/viewer/2022051401/56812d54550346895d925af1/html5/thumbnails/10.jpg)
10
Class BivalviaClams, Oysters, Shipworms
Class BivalviaClams, Oysters, Shipworms
![Page 11: Second-largest phylum in number of species- over 100,000 described](https://reader033.vdocument.in/reader033/viewer/2022051401/56812d54550346895d925af1/html5/thumbnails/11.jpg)
11
Class Bivalvia
• Two shells• Most are filter feeders• No head or radula• Burrow
– Sand, wood, rocks
![Page 12: Second-largest phylum in number of species- over 100,000 described](https://reader033.vdocument.in/reader033/viewer/2022051401/56812d54550346895d925af1/html5/thumbnails/12.jpg)
12
![Page 13: Second-largest phylum in number of species- over 100,000 described](https://reader033.vdocument.in/reader033/viewer/2022051401/56812d54550346895d925af1/html5/thumbnails/13.jpg)
13
![Page 14: Second-largest phylum in number of species- over 100,000 described](https://reader033.vdocument.in/reader033/viewer/2022051401/56812d54550346895d925af1/html5/thumbnails/14.jpg)
14
Giant Clam & Burrowing ClamSiphon
![Page 15: Second-largest phylum in number of species- over 100,000 described](https://reader033.vdocument.in/reader033/viewer/2022051401/56812d54550346895d925af1/html5/thumbnails/15.jpg)
15
Zebra Mussel
• Environmental Pest• Ballast water of ships
from Europe in 1986• Attack be secreting
adhesive byssal threads– Each other
– Other mussels
– Man made objects• Pipes, plumbing
![Page 16: Second-largest phylum in number of species- over 100,000 described](https://reader033.vdocument.in/reader033/viewer/2022051401/56812d54550346895d925af1/html5/thumbnails/16.jpg)
16
Zebra Mussel
• Live in high densities• Feed on phytoplankton• Reproduce rapidly
![Page 17: Second-largest phylum in number of species- over 100,000 described](https://reader033.vdocument.in/reader033/viewer/2022051401/56812d54550346895d925af1/html5/thumbnails/17.jpg)
17
Zebra Mussel
• Attach to native mussels• Killed all native mussels
in Lake Erie
![Page 18: Second-largest phylum in number of species- over 100,000 described](https://reader033.vdocument.in/reader033/viewer/2022051401/56812d54550346895d925af1/html5/thumbnails/18.jpg)
18
Distribution of Zebra Mussel
![Page 19: Second-largest phylum in number of species- over 100,000 described](https://reader033.vdocument.in/reader033/viewer/2022051401/56812d54550346895d925af1/html5/thumbnails/19.jpg)
19
Oysters
![Page 20: Second-largest phylum in number of species- over 100,000 described](https://reader033.vdocument.in/reader033/viewer/2022051401/56812d54550346895d925af1/html5/thumbnails/20.jpg)
20
Pearl formation
Developing pearlDeveloping pearlDeveloping pearlDeveloping pearl
EpitheliumEpitheliumEpitheliumEpithelium
ShellShellShellShell
Irritant lodged between shell and mantle
Layers of nacre secreted around foreign material
![Page 21: Second-largest phylum in number of species- over 100,000 described](https://reader033.vdocument.in/reader033/viewer/2022051401/56812d54550346895d925af1/html5/thumbnails/21.jpg)
21
Scallops
![Page 22: Second-largest phylum in number of species- over 100,000 described](https://reader033.vdocument.in/reader033/viewer/2022051401/56812d54550346895d925af1/html5/thumbnails/22.jpg)
Cephalopoda
Rapid movement; well-developed nervous systems.
Example: Octopus, squid, nautilus
![Page 23: Second-largest phylum in number of species- over 100,000 described](https://reader033.vdocument.in/reader033/viewer/2022051401/56812d54550346895d925af1/html5/thumbnails/23.jpg)
![Page 24: Second-largest phylum in number of species- over 100,000 described](https://reader033.vdocument.in/reader033/viewer/2022051401/56812d54550346895d925af1/html5/thumbnails/24.jpg)
• Originally described from fossils- thought to be extinct since Devonian (350 mya)
• first live specimens recovered in 1952 from 3,600 m depth
• Primitive class, most similar to gastropods, chitons
• Organ systems show metamerism, similar to annelids and arthropods
Class Monoplacophora (“single shell carriers”)
![Page 25: Second-largest phylum in number of species- over 100,000 described](https://reader033.vdocument.in/reader033/viewer/2022051401/56812d54550346895d925af1/html5/thumbnails/25.jpg)
• snails, slugs, nudibranchs, limpets, cowrys, abalones, etc.
• By far the largest and most diverse molluscan class- over 80% of mollusc species are gastropods
• Marine benthic, pelagic, freshwater benthic, terrestrial (mesic & xeric)
• Grazers or predators
• Prominent head, with well-developed sensory structures (second only to cephalopods)
Class Gastropoda (“belly-foot”)
![Page 26: Second-largest phylum in number of species- over 100,000 described](https://reader033.vdocument.in/reader033/viewer/2022051401/56812d54550346895d925af1/html5/thumbnails/26.jpg)
Gastropod shell
Basically a cone, straight or coiled, with new shell deposited at the margin of the open end during growth
New growth
limpets snails
![Page 27: Second-largest phylum in number of species- over 100,000 described](https://reader033.vdocument.in/reader033/viewer/2022051401/56812d54550346895d925af1/html5/thumbnails/27.jpg)
Gastropoda, Prosobranchia, ArcheogastropodaAbalone are large, valuable snails that are harvested and cultured for food and the iridescent shells
![Page 28: Second-largest phylum in number of species- over 100,000 described](https://reader033.vdocument.in/reader033/viewer/2022051401/56812d54550346895d925af1/html5/thumbnails/28.jpg)
![Page 29: Second-largest phylum in number of species- over 100,000 described](https://reader033.vdocument.in/reader033/viewer/2022051401/56812d54550346895d925af1/html5/thumbnails/29.jpg)
Gastropoda, Prosobranchia,
Mesogastropoda
• Example- conchs (Strombus ~50 species)
• The queen conch (Strombus gigas) herbivorous- it is common in the Caribbean and is harvested for its meat and shell.
• This species is economically important and of conservation concern due to overharvesting and pollution
![Page 30: Second-largest phylum in number of species- over 100,000 described](https://reader033.vdocument.in/reader033/viewer/2022051401/56812d54550346895d925af1/html5/thumbnails/30.jpg)
Conch pearls
![Page 31: Second-largest phylum in number of species- over 100,000 described](https://reader033.vdocument.in/reader033/viewer/2022051401/56812d54550346895d925af1/html5/thumbnails/31.jpg)
![Page 32: Second-largest phylum in number of species- over 100,000 described](https://reader033.vdocument.in/reader033/viewer/2022051401/56812d54550346895d925af1/html5/thumbnails/32.jpg)
Some other mesogastropod prosobranchs
cowriestritons
![Page 33: Second-largest phylum in number of species- over 100,000 described](https://reader033.vdocument.in/reader033/viewer/2022051401/56812d54550346895d925af1/html5/thumbnails/33.jpg)
Gastropoda, Prosobranchia,
NeogastropodaExample- cone snails- Conus500-1000 species.
All cone snails inject venom and several of the fish eaters can be fatal to humans
![Page 34: Second-largest phylum in number of species- over 100,000 described](https://reader033.vdocument.in/reader033/viewer/2022051401/56812d54550346895d925af1/html5/thumbnails/34.jpg)
Cone snails are able to engulf their prey whole after paralyzing it with venom
![Page 35: Second-largest phylum in number of species- over 100,000 described](https://reader033.vdocument.in/reader033/viewer/2022051401/56812d54550346895d925af1/html5/thumbnails/35.jpg)
Cone snails have conotoxins- unique venom strategy.
Many different small peptides target different receptors and enzymes. One species may have over 100 different peptides.
Conotoxins have exceptionally high affinity for receptors and a very high target specificity.
Great interest in these peptides as pharmacological agents for research and for drug use
![Page 36: Second-largest phylum in number of species- over 100,000 described](https://reader033.vdocument.in/reader033/viewer/2022051401/56812d54550346895d925af1/html5/thumbnails/36.jpg)
Muricids
Some other neogastropod prosobranchs
Volutes
Whelks
![Page 37: Second-largest phylum in number of species- over 100,000 described](https://reader033.vdocument.in/reader033/viewer/2022051401/56812d54550346895d925af1/html5/thumbnails/37.jpg)
• Bubble snails (cephalaspids)
• Sea slugs
• Nudibranchs: (dorids, aeolids) most are carnivorous, feed on cnidarians
• Sacoglossans: most are herbivorous- many adopt chloroplasts
• Pteropods: (thecosomes, gymnosomes) pelagic, foot modified into winglike lobes
• Sea Hares: (anaspids) important in neurobiology
Subclass Opisthobranchia (gills-behind) some major groups by common name
![Page 38: Second-largest phylum in number of species- over 100,000 described](https://reader033.vdocument.in/reader033/viewer/2022051401/56812d54550346895d925af1/html5/thumbnails/38.jpg)
Bubble shells (Order Cephalaspida) Most are aeolian carnivores on gastropods and annelids
![Page 39: Second-largest phylum in number of species- over 100,000 described](https://reader033.vdocument.in/reader033/viewer/2022051401/56812d54550346895d925af1/html5/thumbnails/39.jpg)
Nudibranchs (Order Nudibranchia)
Shell, mantle cavity and ctenida are gone
Possess cerata (singular = ceras) dorsal projections of the body wall and hemocoel that act as secondary gills
Most are carnivorous and feed largely on cnidarian polyps.
There are two suborders- Doridina (dorids) and Aeolidina (aeolids).
Nudibranchs are some of the most incredibly colorful animals on earth
![Page 40: Second-largest phylum in number of species- over 100,000 described](https://reader033.vdocument.in/reader033/viewer/2022051401/56812d54550346895d925af1/html5/thumbnails/40.jpg)
Dorid nudibranchs
![Page 41: Second-largest phylum in number of species- over 100,000 described](https://reader033.vdocument.in/reader033/viewer/2022051401/56812d54550346895d925af1/html5/thumbnails/41.jpg)
More dorid nudibranchs
(suborder Doridina))
![Page 42: Second-largest phylum in number of species- over 100,000 described](https://reader033.vdocument.in/reader033/viewer/2022051401/56812d54550346895d925af1/html5/thumbnails/42.jpg)
Aeolid nudibranchs (suborder Aeolidina)
![Page 43: Second-largest phylum in number of species- over 100,000 described](https://reader033.vdocument.in/reader033/viewer/2022051401/56812d54550346895d925af1/html5/thumbnails/43.jpg)
Borrowed weaponsAeolids feed on cnidarians and store the functional nematocysts at the tips of their cerata in cnidosacs
Each ceras contains a branch of the digestive gland. A duct connects the cnidosac to the digestive gland.
Stained section of cnidosac showing nematocysts at tip
Digestive gland
cnidosac
![Page 44: Second-largest phylum in number of species- over 100,000 described](https://reader033.vdocument.in/reader033/viewer/2022051401/56812d54550346895d925af1/html5/thumbnails/44.jpg)
Saccoglossan sea slugs-
Shell reduced or absent
most saccoglossans are herbivores that suck plant cytoplasm- some can hijack chloroplasts
![Page 45: Second-largest phylum in number of species- over 100,000 described](https://reader033.vdocument.in/reader033/viewer/2022051401/56812d54550346895d925af1/html5/thumbnails/45.jpg)
Left: sacoglossan Placida showing network of ducts containing green chloroplasts from its algal food.
Right: aeolid nudibranch Pteraeolidia "farms" colonies of brown single-celled algae (zooxanthellae) in its cerata (stolen from cnidarian prey).
Solar-powered Opisthobranchs
![Page 46: Second-largest phylum in number of species- over 100,000 described](https://reader033.vdocument.in/reader033/viewer/2022051401/56812d54550346895d925af1/html5/thumbnails/46.jpg)
Mimicry among dorid nudibranchs and polyclad flatworms- can you tell which is which?
![Page 47: Second-largest phylum in number of species- over 100,000 described](https://reader033.vdocument.in/reader033/viewer/2022051401/56812d54550346895d925af1/html5/thumbnails/47.jpg)
Pterotrachea coronata“sea elephant” A pelagic prosobranch (Mesogastropoda: Heteropoda) that is convergent on pteropods The foot is a sculling fin
![Page 48: Second-largest phylum in number of species- over 100,000 described](https://reader033.vdocument.in/reader033/viewer/2022051401/56812d54550346895d925af1/html5/thumbnails/48.jpg)
Sea hares- (Anaspidea)
internal shell, ink defense, neurobiology subjects