Jen Bartlett & Mark Lynch

Cypriniformes Characiformes Siluriformes Gymnotiformes Ostariophysi

Ostariophysii  Auditory specialization of ear  Weberian complex  Gas bladder  Alarm substances  Almost entirely freshwater fishes  25% of fish, 68% of fw spp.

Weberian Complex  Chain of bones- Weberian ossicles  Connect swim bladder to ear canal  Transmit vibrations

Siluriformes  3000 species, monophyletic group  Synapomorphies:  Live everywhere and include hypogean and trilobictic species  Benthic- heavy bony head, reduced gas bladder  Most lack scales (naked), have barbels  Eat everything: fish scales, blood, wood  Fertilization: internal, external, sperm drinking  Parental care in some species: mouth brooding

Ictaluridae  Only family in Illinois  14 species in IL  Have bony pectoral and dorsal fins to reduce predation

Channel catfish

Mountain madtom

Giant Mekong Catfish 646 pounds 9 feet long Endangered due to dam construction Locals used to catch up to 50 per year, now only 2

Gymnotiformes  Electric eels and knifefishes  173 species  Can generate electrical fields from muscle/nerve cells to stun prey and deter predators  Also used for navigation and communication  Range: fw streams in Neotropics  Lack pelvic, dorsal, and commonly caudal fins, very long anal fin (>140 fin rays) from pectoral girdle to end of body  Restricted gill openings

Gymnotiformes cont.  No maxillary teeth  No schreckstoff or fright response  Anus located anterior to mid-length

Gymnotiformes

Things to not do

Review Questions 1. Is the group Siluriformes a monophyletic group or a paraphyletic group? 2. Do you consider Siluriformes and Gymnotiformes to be sister groups? 3. How do facial phenotypes explain feeding behaviors of the Siluriformes? 4. Why are the Mekong catfish so susceptible to over exploitation? 5. What is the most important thing to not do when swimming in central or south America?