Lecture 26 Reproduction Bony fish Females release eggs cod 9 000 000 Males fertilize by release of sperm No care for fertilized eggs Sharks Males have 2 sex organs called claspers Fertilization is usually internal Females bare fully developed offspring in small numbers cannibalism Offspring are viable at birth Sound touch Lateral nerve system along body very sensitive to pressure fluctuations Shark senses Sight Excellent night vision Motion detectors Smell taste Detect 1 part 1 billion parts Fish schooling What constitutes a school 2 fish 1 leader 1 follower School 3 or more fish whose movements are aligned Schooling types Obligate schooler Permanently in a school Minnows Facultative schooler Intermittent purpose oriented Hammerheads Of 20 000 species of fish 10 000 school Highly biased to small fish Defensive schooling advantages Draw together when threatened Reduced detection Motion confusion Safety in numbers Hydrodynamics Gene pool survival freshwater fish Remarkable behavior Lecture 27 Every living member of the biosphere expands energy in the process of living Motion Circulation Reproduction Thinking Equation for energy flow in the biosphere grazing activity elimination photosynthesis coprophagy birthing Phytoplankton autotrophs 2 needs energy nutrients Coral reef Delicate system Warm water but not too warm Clean seawater Active macro ecosystem Some wave activity but not too much Low nutrient levels but not too low or too high Ecosystem function by passing energy through them Primary producers autotrophs Plankton bacteria algae To photosynthesize light nutrients are required Often near shore environments develop upwelling Exception coral reefs Mutualism displayed by polyps zooxanthallae Reef system recycles low levels of nutrients Lecture 28 Green Moray Eel True fish Slimy for water protection speed and parasite control Removing slime kills it salting Jaw structure Electric eel Freshwater Scaleless Not an eel Sort of a fish but not quite Obligate air breather 80 of body is in the main organ and sach s organs which produce the discharge by controlling ion exchange across membrane Up to 850V and 1 amp Release in a sequence first weak which is sensory second is set of stronger short bursts designed to get prey to move so they can be seen and third is the big discharge which disables the prey It mimics neural impulses sent by the brain for muscle contraction and causes the entire animal to tense up in 4 msecs Sea snakes 60 70 species all from the cobra family venomous extremely so Reptiles they compose 75 of all current swimming reptiles e g turtles Primary adaptation to marine environment is paddle tale Must breath stay under for up to 8 hours Live birth at sea Tripod Fish 3 feet long stand in current and feed on flotsam Lantern Fish Most prevalent fish 60 of deep sea biomass diel migrator Bob Fish Low density flesh no real bone opens mouth to let in food deep sea dweller grows to a foot world s ugliest animal in 2012 Chimeara Distant relative of shark single gill slit diverged 400Mya most mysterious family today were wide spread from fossil record Very old shark Goblin Shark Very deep shark 125 Mya Weak swimmer and sluggish Seems to have pretty good sight Frilled Shark Very ancient shark lineage Could be sea serpent Diel migrator Mouth opens very wide swallow prey whole Lateral line exposed Barreleye Upward looking eyes can rotate forward Dome for protection May steal from local jelly s dome protects eyes Fangtooth Carnivore at depth can t close mouth can see in red and uses it to hunt Pacific Blackdragon Up to two feet Black color to hide some bioluminescence to camouflage and lure black skin to hide bioluminscent prey male up to 3 inches and doesn t feed lives only to breed Probably a survival technique to insure gene mixing Viperfish Can t close mouth for teeth Vertebrae shock absorber has a bioluminescent lure and several other lights for camouflage About a foot Fierce predator Anglerfish Bioluminescent lure Wide spread Male much smaller embeds himself on female gets absorbed except for testes Female can have up to 6 attached males Gulper Eel Gets six to eight feet long Big mouth can swallow fish much larger than itself Tail has bioluminescent cells that it might use for fishing Black Swallower Can eat things 10 times its size Can die from overeating There is an active ecosystem in the deep sea that rivals the one at the surface 50TW compared to 12TW Powered up by marine snow and fish drop Full trophic food web beyond phytoplankton Zooplankton up to top carnivores Diel migration Inhabitants have unique adaptations to the environment Bioluminescence Sexual dimorphism Anatomical changes for living in food scarce Environment Gelatinous tissue Lecture 29 The Gaia Hypothesis Theory The Biosphere is a necessary and key player in the functioning of the Earth as a stable habitable environment A Prediction Stability implies mechanisms within Gaia will enforce the habitable planet in spite of perturbations The story of Gaia revolves around Oxygen Origins Sulfur Planetary Temperature Ocean Salinity content These are also interrelated Oxygen Our atmosphere is highly unlikely 21 Oxygen 78 Nitrogen Billion times too much 1 Methane but still way too much by 1035 400ppm carbon dioxide Consider Venus and Mars Atmospheres are mostly carbon dioxide History of oxygen illustrates Gaia stability through feedback loops Both organic and inorganic Limiting process is unclear but essential Oxygen was toxic to early anerobes opened the world to multi cellular aerobes but ice ball earth as well due to c02 collapse Sulfur Global Sulfur budget was not balanced Lovelock postulated a sulfur cycle involving the oceans Algae add methyl groups to other compounds perhaps to make an unwanted chemical somewhat more volatile Also a particular sulphur precursor to DMS helps regulate cellular ionic balance Measured at sea also CFCs Planetary Temperature Faint Young Sun Hypothesis Relatively constrained temperature range over geologic time Planetary homeostasis like body temperature control Most famous quantitative model Daisy World Planet existing under aging sun 2 types of daisies Growth characteristics are temperature dependent identical They compete for soil White Black Ocean Salinity Ocean receives 500MT year salt Corresponds to 80My time scale Over last few 100My ocean salinity is stable 3 5 Very important as salt water becomes toxic to plankton 6 Limiting mechanism is not clear
View Full Document
Unlocking...