Introduction to Marine Fishes Marine Vertebrates
Introduction: • Fish are the first vertebrates to appear more than 500 million years ago. • Fish are the most abundant vertebrates in terms of both species and individuals. • 58% of all fish are marine.
External Fish Anatomy:Vocabulary to know… Dorsal fins Caudal fin (tail) Pectoral fins Anal fin Pelvic fins
External Fish Anatomy:Vocabulary to know… Lateral line Eye Mouth Peduncle Operculum (gill cover)
Jawless Fishes Kingdom: Animalia Phylum: Chordata Class: Agnatha Subclass: Myxini & Petromyzontida Species: About 88
Jawless Fishes • Ancient group of vertebrates*, with several extinct groups • Only two extant groups (alive today) • Lampreys • Hagfish
Characteristics of Jawless Fishes: • Lack jaws; feed by suction w/ round mouth and rows of teeth. • Body is cylindrical and elongated. • Lack paired fins. • No scales.
Jawless Fish: Hagfish • Feed mostly on dead or dying fishes. • Eyeless, jawless, and dependent on their sense of smell to find food, hagfish invade feeble or dead fish by entering through their mouths and settling in their stomachs, where they secrete a slimy substance that protects them from the digestive juices of their hosts. They then eat their hosts from the inside out.
Jawless Fish: Hagfish Sliming sharks more
Jawless Fish: Lamprey • Primarily freshwater fishes, but some move to the sea as adults. • Attach to fishes and suck their blood.