Marine Biology - Exam Notes

General Class Information

Students are not reading the questions carefully and are answering with information that is not relevant.
The importance of understanding the context and applying scientific terminology correctly is emphasized.
Memorization is not the goal; the focus is on understanding and application.
Spelling matters because clear communication is important in science.
The small class setting allows for discussion and clarification.
Taking detailed notes is beneficial, but structuring them to identify the most important points is crucial.
Context is very important; create a story around the information to help with understanding and retention.

Phylum cnidaria is split into four classes: hydrozoans, schizoantzones, empazones, and hematoans.
Phylum is a broader taxonomic designation than class.
The classification of organisms changes as new information is discovered.
The older classification system is used because it provides a better split of the adaptations these organisms have and is more intuitive.

Analytic: the third phylum to be covered, and six phyla will be covered overall.
Analytic animals are the first animals discussed that have a gut that goes all the way through them.
Sponges lack a mouth, digestive system, tissues, and organ systems; they are asymmetrical.
Cnidarians have radial symmetry around a central mouth cavity and a crown of tentacles.
Cnidarians are 90% water and have a simple neural network.
Examples of cnidarians include corals, jellies, and colonial animals like Velella velella (by-the-wind sailor), which belongs to the class hydrozoa.
Colonial animals like the Portuguese man-of-war consist of individual animals working together to build structures like a sail.

Annelids are bilaterally symmetrical, segmented worms with a gut running from mouth to anus.
Their segmented bodies allow for controlled expansion in sections.
Earthworms play a crucial role in introducing air to the soil.
Annelids are divided into three classes: polychaetes, oligopita, and hairdenia.
- Polychaetes have diverse feeding strategies.
- Oligopita are mostly earthworms that eat decomposing material.
- Hairdenia are leeches that suck blood.

Earthworms have complex digestive systems to extract nutrients from dead organic matter.
Leeches have simple digestive systems because they feed on nutrient-rich blood.
The adaptation of animals to their food sources influences their digestive systems.
Earthworms grind their food to extract nutrients, while leeches directly suck processed nutrients from blood.
Complexity in food eaten equates to complexity in the digestive system.

Some polychaetes have symbiotic relationships with bacteria.
Chemosynthesis, not photosynthesis, is used by bacteria in the deep ocean because it is dark.
Chemosynthesis may have predated photosynthesis.
Tube worms were discovered in the 1970s and rely on chemosynthesis.
Colleen Kavanaugh discovered that bacteria in tube worms use sulfur energy (sulfide to sulfate conversion) to create sugars.
The sugars go to the worm similar to how zooxanthellae distribute nutrients to coral hosts.
Photosynthesis and chemosynthesis are parallel processes; one uses chemicals while the other uses light to synthesize.
In hydrothermal vents, hydrogen sulfide is used as an energy source by bacteria in chemosynthesis.
The bacteria make sugars, which feed the worms.

Photosynthesis and chemosynthesis do not produce energy; they use energy to produce sugars.
Sugars are then used to liberate energy by breaking the bonds.
The worm provides the bacteria with sulfide and oxygen.

Hydrothermal vents are caused by rifts between continental plates and spew volcanically superheated water.
Tube worms (Riftia pachyptila) are giant worms that live near hydrothermal vents and have no mouth, gut, or anus.
They have an organ called a trophosome filled with sulfur crystals and symbiotic sulfur-oxidizing bacteria.
The bacteria use hydrogen sulfide from the vents as an energy source in chemosynthesis.
Hydrogen sulfide and oxygen are carried by the blood to the trophosome.
These vents are found 7,500 meters below the surface.

In photosynthesis, carbon dioxide and water are transformed into sugars with the help of sunlight energy.
In chemosynthesis, sulfide and oxygen react spontaneously and release energy, which is then used to drive the conversion of inorganic substances to organic substances.
Chemosynthesis can occur in high hydrogen sulfide environments but can also occur in other environments with other chemicals such as in methanogenesis.

Six classes of mollusks are: cephalopods, bivalves, gastropods, polyplacophora, and staphopoda.
Examples of bivalves include oysters, mussels, clams, and scallops.
Examples of gastropods include abalone, snails, and nudibranchs.
Examples of cephalopods include squid, cuttlefish, and octopuses.
Tusk shells are called tusk shells because they look like tusks. These are of the class staphopoda.
Chitons are the most ancient class of the mollusks phylum.
In California, the biggest titan in the world is called the gumbo titan

Squid are cephalopods that live in all the world's oceans.
They are a reliable food source for whales, dolphins, sharks, seabirds, fish, and other squid.
Squid are fearsome ocean predators.
Some species swim together in shoals as defense against predation.
They rely on large, well-developed eyes and a secondary sensory system made from tiny hair cells.