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III. Arthropods A. Member of superphylum ECDYSOZOA 1. Grow by molting: shed their exoskeleton 2. Nematode worms are also in this group B. About 80% of all described species of animals are arthropods. Relative Numbers by Taxa. Arthropods (continued)
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III. Arthropods A. Member of superphylum ECDYSOZOA 1. Grow by molting: shed their exoskeleton 2. Nematode worms are also in this group B. About 80% of all described species of animals are arthropods
Arthropods (continued) • C. Horseshoe Crab, Limulus, is not a crustacean • 1. CHELICERAE • a. 1st pair of mouth appendages • b. Stab (up & down motion)
C. Horseshoe Crab, Limulus (continued) 2. Natural History a. Inhabit shallow marine waters with sandy bottoms b. Burrow beneath surface preying upon worms in sand c. Lifespan as long as 19 years d. Mature at about 9 years e. More common east and west of Mobile Bay because of the lower salinity
Horseshoe Crab, Limulus (continued) • 3. Blood is harvested for Limulus amebocyte lysate (= LAL) • a. Coagulates in presence of bacteria • b. Used to screen pharmaceutical products for bacterial contamination
Aggregation of Limulus, the Horseshoe Crab
D. Crustaceans 1. Most have 3 body regions a. Head a. MANDIBLES move sideways b. Maxillae & maxillipeds (1) Chemosensors (2) Handle and manipulate food
Three body regions (continued) • b. THORAX • (1) Middle region • (2) CARAPACE • (a) Found in lobsters, crabs & shrimp • (b) Head & thorax fused to form a shield- like dorsal covering • (3) Location of walking appendages
Three body regions (continued) • c. ABDOMEN • (1) Posterior (May curl up under thorax) • (2) Location of reproductive appendages
D. Crustaceans (continued) 2. Isopods a. Flattened dorsal-ventrally
2. Isopods (continued) b. Commonly encountered as ectoparasites in fish gills
2. Isopods (continued) c. A scavenger species that lives in the sand at Dauphin and Sand Islands can give tiny “pin prick” bites to the feet of waders
D. Crustaceans (continued) 3. Decapods a. Crabs, shrimp & lobsters b. Characteristics (1) 10 walking legs (including claws) (2) Carapace encloses gill chamber
Cheap Thoughts by Jack O’Brien Be aware of what you eat
IV. Bryozoa (BRYO = Moss; ZOA = Animals) A. Characteristics 1. Colonies on hard substrates a. Some are sheet-like b. Some form erect colonies
A. Bryozoan Characteristics (continued) 2. LOPHOPHORE a. Characteristic feeding organ (1) Ciliated tentacles surround mouth (2) Filter-feeders
Lophophore of a bryozoan http://en.wikipedia.org/wiki/File:Freshwater_Bryozoan234.JPG
2. Lophophore (continued) b. Members of superphylum LOPHOTROCHOZOA (1) Linked by similar DNA (2) Contains phyla with trochophore larvae (a) Mollusks (b) Annelids (3) Contains phyla with lophophores
A. Bryozoan Characteristics (continued) • 3. Individuals are called ZOOIDS • a. Less than 1 mm in width • b. Encased in an organic box from which the lophophore extends
Bryozoan Zooids http://www.google.com/imgres?imgurl=http://neogenebryozoans.myspecies.info/files/Bryozoan%2520figure%25201.jpg&imgrefurl=http://neogenebryozoans.myspecies.info/bryozoans&h=600&w=617&sz=41&tbnid=iwBUnIoCvTTpqM:&tbnh=93&tbnw=96&zoom=1&usg=__ygmONRLr4UDKM6TjMlQ7keaAeGg=&docid=rbMa5LZPi76LpM&sa=X&ei=kNTxUYqdL4S-8ATP24CoAQ&ved=0CDIQ9QEwAg&dur=489
A. Bryozoan Characteristics (continued) • Bugula stolonifera • a. Very common in the Gulf of Mexico • b. Grey-buff colored branches http://www.google.com/imgres?imgurl=http://www.cryptosula.nl/photos/Bugulastoloniferaweb.jpg&imgrefurl=http://www.cryptosula.nl/Bugulastolonifera.html&h=450&w=544&sz=39&tbnid=JQUHCd7yKG3VkM:&tbnh=90&tbnw=109&zoom=1&usg=__CJRQgeVYGyIMn_MwZ9iNgPW0bh4=&docid=8Cgyq-zjaCZHRM&sa=X&ei=ItfxUa33BoXm8QSNroHoDg&ved=0CDIQ9QEwAg&dur=367#imgdii=_
V. Echinoderms A. Characteristics 1. Radial symmetry 2. Calcareous internal skeleton 3. Usually 5 rays or body divisions
Happily for nerds who like echinoderm art, most artists can count to five Photo by J. O’Brien, June 2014
A. Echinoderm Characteristics (continued) 4. TUBE FEET provide locomotion a. Projections of body wall with sucker- like tips b. Fluid-filled
V. Echinoderms (continued) • B. Sea stars • 1. Slow moving predators • 2. Major impact upon intertidal bivalves • 3. MUSSELS ON THE HALF SHELL: • a. Extrude stomach between shells of bivalve • b. Secrete digestive enzymes into bivalves’s mantle cavity • c . Absorb nutrients without ingesting bivalve’s hard parts
In the Antarctic Ocean, some sea stars are quite large Photo by J. O’Brien, June 2014
Barrel of Dead Sea Stars Photo: J. O’Brien, 2011
V. Echinoderms (continued) C. Sea urchins 1. Skeletons composed of 5 plate-like ossicles 2. Tips of some spines contain venom that is very painful to humans 3. Omnivores 4. Removal of predators (sea otter) results in overgrazing of kelp beds
Echinoderm Endoskeletons Photo: J. O’Brien, 2011
Echinoderms Adorning a Plastic Christmas Tree Photo: J. O’Brien, 2011
V. Echinoderms (continued) • D. Sand dollars • 1. Flattened • 2. Mucus used to catch small prey
D. Sand dollars (continued) • 3. May plow through sand or stand upright facing current
V. Echinoderms (continued) E. Sea cucumbers 1. Sausage-shaped 2. Tentacles enclose mouth 3. RESPIRATORY TREES a. Outgrowth of hindgut b. Water drawn into hindgut where respiratory exchange occurs c. Many animals live here
Sea cucumbers (continued) • 4. Defense mechanisms • a. Some species poisonous • b. Portions of respiratory tree ejected out anus and entangle predators
VI. Phylum Chordata • A. Characteristics • 1. NOTOCHORD: Dorsal support rod (not bone) • 2. Gill slits
VI. Chordata (continued) • Invertebrate chordates • 1. Lancelets • a. Notochord present entire life-cycle • b. Adults buried in sand • c. Feed on plankton • d. Amphioxus in Mobile Bay
Garrison, 2005 Oceanography: An Introduction of Marine Science, p. 368 Castro & Huber, 2003, Marine Biology, p. 147 Cephalochordate Amphioxus