Challenges of Life in the Sea Chapter 4

Temperature Metabolic reaction time – Reaction time is faster at high temperatures – Reaction time is slower as temperature cools down Reactions occur about twice as fast with a 10 degree C temp raise. At extreme temperatures enzymes cease to function properly

Ectotherms Heat is quickly lost to the environment. “Cold- blooded” All ectotherms are poikilotherms- as the temperature of the environment changes so does their body temp and metabolic rate.

Regions by Temp.

Cool waters Tunas, sharks (large fishes) – maintain body temperatures because of the metabolic heat produced by large muscles. Able to remain active even in cold waters. – Not as limited geographically Endotherms- metabolic rate significantly raises their body temperature

Homeotherms Mammals and birds are able to keep their body temperatures more or less constant even when the external temperature varies. “warm blooded” Control their metabolism. Produce heat by burning fats and energy rich molecules – Cost is high so they reduce cost with insulation

Surface to Volume Ratio The amount of surface area relative to the total volume of an organism In other words, Surface-to-volume ratio – Determines how rapidly heat and materials flow in and out.

What determines S/V Size of the organism As organism grows, the volume increases faster than the surface area. Small organisms have larger S/V than big ones

Small organisms Especially single celled organisms rely on simple diffusion across their surfaces for the exchange of materials.

Large organisms Large organisms must develop supplementary mechanisms like respiratory and excretory systems.

Bathroom break

Perpetuating life One of the most basic characteristics of living things is the ability to reproduce Produce a new individual to perpetuate the species, pass on characteristics of the species through genetic information. – Heredity

Modes of reproduction Asexual reproduction- primary method for single celled organisms All form of asexual reproduction are similar, offspring inherit all the genetic characteristics of the parent. – Clones Single celled organisms and multicellular

Fission Sea anemones – simply split in half to form two smaller anemones Kao Kao

Reproductive strategies Budding- parent develops small growths buds – The buds eventually break away Vegetative reproduction – send out various kinds of runners that take root and then sever connection to parent – Genetically identical to the parent

Sexual reproduction Multicellular and some unicellular organsims Sexual reproduction- new offspring arise from the union of two separate cells – Gametes Organisms that reproduce sexually have a special kind of tissue – Germ Tissue Germ cells are capable of a second type of division- MEIOSIS

Mitosis vs. Meiosis

Reproductive Strategies Broadcast spawning, Brooding, Mouthbrooding Some invest a lot of time and energy into a few offspring Some have larval stages, some develop from an egg some some asexual some sexual some do both

Reproductive Strategies Reproductive strategy – the particular combination of methods used by a given species. Strategy used depends on – Size – Where it lives – How it lives – What kin of organism it is

Diversity Theory of Evolution – gradual alteration of a species genetic make up supported by a vast body of evidence.

Evolution Genetic differences in ability to find food, avoid being eaten, reproduce, metabolism and so on Best adapted for the environment- more offspring This process is called natural selection

Other strange reproductive strategies… Some fish have the ability to change sex Sharks – Ovoviviporous- egg inside the mother’s body, live birth – Egg laying sharks

Zebra Shark Egg Case

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