The Siluriformes & Gymnotiformes

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 Questions1. 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?