The Diversity of Fishes:An IntroductionLecture 2– August 26
WHAT ISN’T EVOLUTION?Evolution doesn’t work in a straight line, it lacks direction
Phylogenetic definitionAll chordates are fish; however, for this class, we will limit the scope of “fish”to occupy aphylogenetic position from cephalochordates(lancelets) up to amphibians.
Fish Evolution•Fishes have been around for nearly500 million years (predating manby almost this entire period and allother vertebrates by nearly 100million years)The vertebrate bauplan evolved from our aquatic fishancestors◦Body arrangement/jaws/limbs◦Vertebrate eye/vision◦Internal fertilization/intrauterine nourishment◦Viviparity◦Big brains
The vertebrate bauplan evolved from our aquatic fishancestors◦Body arrangement/jaws/limbs◦Vertebrate eye/vision◦Internal fertilization/intrauterine nourishment/placenta◦Viviparity◦Big brains◦Respiration – How do fish breath?Embrace your inner fish
The Diversity of Fishes•32,000 valid living species•515 families•62 orders–108 jawless fish spp. (70 hagfish, 38 lamprey)–970 cartilaginous fish spp. (403 sharks, 534 skates, 33chimeras)–30,000 + bony fishes
Habitat of Fishes•70% of the Earth’s surface is covered in water•Fishes are found in all aquatic habitats–Thermal hypersaline springs 104° F (40° C)•Soda Lake Cichlid – Tilapia spp.–Antarctic Waters <0° F–Caves/ground water–Anoxic swamps–Mud–Hydrothermal vents–High elevation (5km above sea level)–Deepest ocean (8km – 5 miles down)•Abyssobrotula galatheaefound in the Puerto Rican Trench