Just Keep Swimming MUSCLES Attach to backbone Red

Just Keep Swimming

MUSCLES • Attach to backbone • Red myomeres – high myoglobin content stores oxygen for long distance swimming • White myomeres – less myoglobin content allows for short bursts of speed.

CIRCULATORY &RESPIRATORY • Heart has 2 chambers: atrium & ventricle • Gills have high surface area for gas exchange with lamellae on filaments • Spiracles (openings behind eyes) let in water when mouth is closed in sharks.

EXCRETORY • Marine fish drink seawater continuously – Release salt across gills – Excrete thick urine • Freshwater fish do not drink water • Water moves into cells constantly • Excrete lots of dilute urine

Reproduction • Most are separate sexes • Types: - Oviparous – release eggs & external fertilization - Ovoviviparous – internal fertilization of eggs, hatch internally & born live - Viviparous – internal fertilization, embryo gets food from female’s tract

Reproductive Behaviors • Mating rituals – dancing, stirring sand • Hermaphrodites – both sexes to improve offspring success • Sex reversal – dominant male or female gone, replaced by strongest

Sensory Adaptations • Taste bud – on mouth, lips, fins, skin • Smell – olfactory sacs in nostrils • Vision – round lens focuses by Moving closer or farther away Some fish have color vision Sharks have nictitaing membrane for protection

Sensory Adaptations • Hearing – inner ear helps with balance & equilibrium • Lateral line – canals on sides have sensory cells to detect vibrations • Ampullae of Lorenzini – detects weak electrical fields of prey (in sharks)

SCHOOLING BEHAVIOR • MOVE IN UNISON, SAME SIZE & MAINTAIN DISTANCE. FEEDING, MATING & PROTECTION

WHY MIGRATE? ? • Regular mass movement from 1 place to another for: feeding, mating & birthing • Anadromous – spawn in freshwater, spends most of life in sea. EX: salmon • Catadromous – spawn at sea, return to freshwater to live. EX: eel

BODY SHAPE • Matches lifestyle – Streamlined: fast swimmers (nektonic) – Laterally compressed: quick turns & short bursts of speed – Flattened: bottom dwellers (benthic) – Elongate: live in narrow spaces – Irregular: concealment

COLORATION • • Pigments called chromatophores Bright colors: tropical habitat or poisonous Cryptic: blends with background Disruptive: stripes, bars, spots, eye shapes will confuse predator

COLORATION (cont. ) • Countershading: light on ventral (white or silver) & dark on dorsal disguise in open water. • Dark shades: black, red, blue and purple in deep water where there is no light