Achilles Tangs, (Acanthurus achilles) Chapter 4 – Some Basics of Biology • Organisms have precise chemical and physical organization. • All organisms require energy (the ability to do work) to maintain themselves and grow. • The large number of chemical reactions that sustain life can be referred to collectively as metabolism. • Organisms use energy to maintain homeostasis, which is maintaining stable internal conditions that are different from their environment. Ways of obtaining energy • Autotrophs – capture energy from the environment and use it to make glucose (a sugar); Glucose is broken down during respiration and used for growth, etc. Photosynthesis is the most common way organisms make their own energy. Capturing energy from the sun to build complex molecules. Chemosynthesis uses chemicals in the environment to build sugars, NOT sunlight. Seen around hydrothermal vents. • Heterotrophs – don’t make their own energy, they consume other organisms and use stored energy found in tissues for growth, etc. Both heterotrophs and autotrophs both engage in respiration as a process of using the energy no matter what the source. Primary Production • Primary production is the net gain in organic matter that occurs when autotrophs make more organic matter than they need, usually by photosynthesis. Only CO2, water and light are needed to make glucose by photosynthesis but additional materials are needed to convert the glucose into other compounds. Examples: Proteins, Lipids, nucleic acids These raw materials are called nutrients. Nutrients Complex organic molecules. • Primary production requires nutrients as well as light. • Nitrogen and Phosphorous are usually the most important nutrients for plant growth in the ocean. Often the limiting factor for growth. Slate Pencil Urchin (Heterocentrotus mamillatus) Warm-Up 3/9 1. Why is primary productivity in an area strongly associated with phosphorous and nitrogen levels? 2. How do heterotrophs and autotrophs differ? 3. How are autotrophy and heterotrophs the same? Cellular composition • Simple Cells Prokaryotes – Simplest and smallest cells (bacteria) – No membrane‐bound organelles or nucleus – Cell wall • Complex Cells Eukaryotes – Nucleus with chromosomes – Organized and complex – Organelles with specialized functions • Unicellular- One celled organisms that can carry out all functions of life. – Nearly all prokayotes are unicellular • Multicellular- Multiple cells working together to form an organism. Cells become specialized for particular jobs. – Nearly all multicellular organisms are Eukaryotic Challenges of life in the sea Salinity • Diffusion- Movement of molecules from an area of high concentration to one of low concentration. – Whenever the internal composition of a cell differs from that on the outside, substances tend to move in or out of the cell by diffusions. • Cell membranes are selectively permeable and allows some substances to enter and leave the cell but blocks others. • Complex molecules cannot leave the cell, but water and other small molecules can still easily pass through. • Osmosis- diffusion of water across the cell membrane. • This movement of water must be dealt with for an organism to survive in an aquatic environment. Regulation of salt and water balance • Osmoconformers- Organisms that don’t actively maintain a salt and water balance. Their internal concentrations change as the salinity of the surround water changes Blue-spotted Jawfish (Opistognathus rosenblatti) Warm-Up 3/10 1. What is the difference between hypotonic and a hypertonic solution? 2. How does diffusion pose a challenge to animals maintaining homeostasis (life)? 3. Why don’t large molecules and proteins diffuse out of cells? • Osmoregulators- Control their internal concentrations to avoid osmotic problems. Have limits, but can tolerate salinity changes better than conformers. Maintain an internal environment that is different from the surrounding water Marine Osmoregulation • • • • Water lost via osmosis through skin and gills. Water is replaced by drinking. Actively excrete the accumulated salt via gills. Produce small amounts of concentrated urine. Freshwater Osmoregulator • • • • Water gained via osmosis through skin and gills. Do not drink. Salt lost via diffusion. Actively collect via gills. Produce high volumes of dilute urine. • Marine birds, reptiles and some plants have special glands that rid them of excess salt Temperature Regulation • Ectotherms – “cold‐blooded” generate heat through their metabolism which is quickly lost to the environment. Body temp is about the same as the environment. • Endotherms – “warm‐blooded” metabolic heat is retained raising body temperature above surroundings. Surface to Volume Ratio • Small organisms can lose body heat and materials more rapidly than larger organisms • The surface of a cell, its membrane, is the site of exchange between its interior and its external environment. • This surface must allow sufficient exchange to support the contents of the cell. Nutrient intake and waste elimination both rely upon diffusion. • As an object increases in size its volume increases as the cube of its linear dimensions while surface area increases as the square. • As these cubes illustrate the surface area to volume ratio of a small object is larger than that of a large object of similar shape. • This means that larger organisms must have respiratory and excretory systems to compensate for the larger volume as diffusion cannot occur quick enough. Methods of Reproduction • Asexual (Vegetative) Reproduction • Results in clones – genetically identical to parent • Cell Fission and Budding Fission Sexual Reproduction • Union of two different gametes (egg & sperm) • Fertilization ‐ Results in genetically different offspring (embryo) • Egg – contains a lot of cytoplasm and the organelles; yolk (nourish embryo) • Sperm – head contains genetic material only • Larval stage – present in most marine organisms • Immature stages that an organism undergoes to reach sexual maturity; usually visually completely different than adult. Crab Larva Reproductive Strategies • Reproductive Strategies refers to the Methods used by a given species for reproduction and care of young Internal Fertilization • Fertilization takes place inside the female body. • Copulation is the process of transferring sperm from the male to the female via a specialized organ. External Fertilization Sperm unites with egg in the open, rather than inside specialized organs within the bodies of the parents • Broadcast Spawning (External Fertilization) – sperm and egg release in large numbers directly into the water; no parental care Barrel Sponge Releasing Gametes Green Sea Urchin Releasing Gametes Diversity of Life in the Sea • There is a tremendous amount of diversity in the oceans. How did it happen? Theory of Evolution and Natural Selection • (Charles Darwin – 1800’s) • Best‐adapted individuals will produce more offspring and pass on their favorable characteristics. • Populations continually change in response to their environments; they evolve (change over time) Phylogenetics (Phylogeny) study of evolutionary relationships among organisms • Think of this as an extended family tree. • You can use a family tree to figure out how closely related you are to someone else. • We are trying to figure out how closely related we are to other species. Cladogram: – a tree‐shaped diagram showing evolutionary relationships and the points where species appear to have diverged from common ancestors Classification of Living things –Domain –Kingdom –Phylum –Class –Order –Family –Genus –Species (Dragon Kings Play Chess On Fine Gold Squares) All of the organisms in the world are assembled into three domains and six kingdoms • Species: – populations who share common characteristics – Can breed with each other – Produce fertile offspring One Species Many Species Horse + Donkey = ? Mule (Infertile) Zebra + Horse = ? Zorse (Infertile) Dolphin + False Killer Whale = ? Wholphin (fertility unknown) Polar Bear + Grizzly Bear = ? Grolar Bear • Genus: – Group of very similar species (ex. Felidae “cats”) • Binomial Nomenclature: – two‐name system of identifying organisms (ex. Homo sapiens) Weird scientific names • There’s an entire genus of mites named Darthvaderum. There’s even a wasp named Polemistus chewbacca • There are a couple of flies named Heerz lukenatcha and Heerz tooya. • In 2002, Neal Evenhuis named a bunch of flies, including Pieza rhea, Pieza pi, and Pieza kake. • Scientists say that Scaptia beyonce has a “large golden bottom”