1. Characteristics of Marine Life
Chapter 4
Ms. Cuthrell
Marine Biology
4th Period

2. Levels of Organization
A cell is a self-contained unit that can carry out all the functions necessary for life.
Unicellular: one-celled organisms, all prokaryotes (Bacteria), some eukaryotes (Protists)
Multicellular: organisms having more than one cell, most eukaryotes (Animals, Plants, Fungi)
The human body contains 100 trillion cells.
In multicellular organisms, each cell has a specialized job in the body.
Level of organization: the extent or specialization and organization of cells.

3. Organization Within the Body
All cells are self-sustaining and go through all the processes of life that the body needs with little to no interaction with other cells.
Tissues: specialized, coordinated groups of cells.
Ex: muscles tissues/ nervous tissue
Organs: groups of tissues that carry out specific functions.
Ex: heart, brain, stomach, skin
Organ systems: organs act together for specific functions.
Ex: nervous, digestive, circulatory, reproductive

4. Interactions Among Individuals
Not only are there different levels of organization within individual organisms, but individuals interact with each other at higher levels of complexity.
Species: a specific type or organism that can interbreed to produce fertile offspring.
Population: group of organisms of the same species in one place at one time.
Community: populations of different species that occur in the same place.
Ecosystem: a community or group of communities living in the same physical (non-living) environment.

5. Challenges of Life in the Sea
Every habitat has its own unique set of characteristics and presents special challenges to organisms that live there.
Marine organisms have to cope with different living situations that terrestrial (land) organisms.
Each specific marine habitat poses special needs and difficulties all its own.
Planktonic organisms: float at the top of the water.
Benthic: live on the bottom of the ocean.
Nekton: Swim through the water.

6. Challenges of Life in the Sea
Salinity affects all marine organisms living in ocean water.
Diffusion and Osmosis:
Diffusion: molecules or ions in water will move from an area of high concentration to low concentration across semi-permeable membranes until they reach equilibrium.
Osmosis: water molecules will diffuse into or out of cells to try to regulate/ control concentrations of molecules or ions.
Both of these processes are carried out through passive transport and require no energy (ATP)!

7. Challenges of Life in the Sea
If organisms need to move something out of the cell from low to high concentration against the concentration gradient, they will use active transport which requires energy from the organism (ATP).
Ex: getting rid of excess sodium, taking in particles of sugar or amino acids from surroundings
Active transport is so important that it represents over one-third of a cell’s total energy use.

8. Challenges of Life in the Sea
Marine organisms have adapted to problems of maintaining the proper balance of water and salts in various ways.
Some do no actively maintain salt and water balance at all; their internal concentrations change as the salinity of the water changes (osmoconformers).
Osmoconformers have to stay where the salinity of the water and their fluids inside the organism match.

9. Challenges of Life in the Sea
Other organisms osmoregulate, or control their internal concentrations to avoid osmotic problems.
These organisms will adjust the concentrations of solutes in their body fluids so that the overall concentration of their fluids matches that of the water outside.
For some osmoregulaters, it doesn’t matter if the materials outside and inside of the organism are the same, as long as the amounts are the same.
These organisms will adjust the specific chemical needed to match the salinity outside.

10. Challenges of Life in the Sea
The most common form of osmoregulation in fish is done by drinking seawater to obtain any water lost by osmosis because their blood concentration is said to be different from surrounding sea water.
Fish produce very little urine and must get rid of salts taken in while drinking seawater by excreting it immediately through urine or, more commonly, their gills.

11. Challenges of Life in the Sea
Freshwater fish are opposite of marine fish and their blood has a higher concentration of salt than their surroundings.
Marine birds, reptiles, and some marine plants, also have special cells or glands to get rid of excess salt.
Marine plants and most algae have the added advantage of a cell wall to keep them from swelling and bursting during changes caused by osmotic water gain.

12. Challenges of Life in the Sea
Temperature:
Organisms are greatly affected by temperature.
Metabolic processes speed up in warmer temperatures and slow down in cooler temperatures.
Enzymes will stop functioning in extreme temperatures.
Most marine organisms are adapted to live in specific temperature ranges.
Organisms found in polar regions cannot survive in tropical regions and organisms found in tropical regions would die in polar regions because of adaptations to these environments.

13. Challenges of Life in the Sea
Ectotherms: “cold-blooded” organisms, internal heat is quickly lost to the environment and the environment has a great impact on their body temperature.
Endotherms: “warm-blooded” organisms, internal heat is stored relatively easily and therefore is wormer and not affected by the organism’s surroundings.
Many warm-blooded organisms are known as homeotherms because they maintain body temperature through homeostatsis.
To conserve heat, some mammals and birds will insulate themselves with feathers, hair, or blubber.

14. Perpetuating Life Reproduction:
All organisms need to reproduce to keep their species from going extinct.
To do this, organisms go through two processes to be successful:
Making new individuals.
Pass on genetic information.

15. Perpetuating Life Asexual Reproduction:
1 organism will divide into two identical organisms.
Cell fission: Cells divide to produce daughter cells.
This process is also known as mitosis.
Primary way single-celled organisms reproduce.
Fission: Sea anemones split in half to create new anemones.
Budding: new organism buds off of parent organism.
Vegetative reproduction: plants send out various kinds of runner that then take root and form new organisms.

16. Perpetuating Life Sexual Reproduction:
Two parents come together with gametes (sperm and egg) to form an offspring genetically different from both parents.
Meiosis: process of forming gametes, all gametes are genetically different from each other.
Gonads: germ tissues that form gametes. (females:ovaries, males: testes)
Haploid: containing half the number of chromosomes.
Diploid: containing a full set of chromosomes (pairs).

17. Perpetuating Life
When a sperm and egg combine for the first time, the first cell of the new organism is called a zygote.
This will later form into an embryo, then a fetus.
Some organisms will form into a larval stage which will look completely different than the adult organism.
Spawning: eggs and sperm are released directly into the water column.
Reproductive strategies depend on the organism’s size, where and how it lives, what kind of organism it is, and its environment.