Exam Study

Question 1

1. What are coccolithophores? What are their characteristic features? Where in marine environments do they usually occur? What is their main ecological significance?

Answer 1

A Coccolithophore is a type of phytoplankton, it is also photosynthetic haptophyte (protist).
Characteristics include size ~2 to ~20um (nanoplankton), the cell surface covered by coccoliths (disc shaped calcareous plates).
Coccolithophores occur everywhere but most species are found in subtropical area.
Coccolithophores play an important role as primary producers in nutrient poor areas, this is their main ecological significance.

Question 2

2. What is a virus? Outline the diversity, abundance and ecological significance of marine viruses.

Answer 2

A virus is an infective agent, it’s genetic material that’s surrounded by a protein coat end requires a host to provide nutrition and reproduce.
Viruses are known to be likely the most diverse group and are also very abundant.
Viruses play an important role in creating important agents of mortality as they cause disease in organisms ranging from bacteria to whales, this also plays a major role in biogeochemical cycles.

Question 3

3. What are the Rhodophyta, what are their characteristic features and where would you expect to find them?

Answer 3

Rhodophyta is the phylum of a marine algae in which chlorophyll is commonly masked by a red pigmentation.
Characteristic features include multicellular organism, single thylakoid lamellae with phycobilin granules on the surface.
Most commonly found in the benthic region.

Question 4

4. What is a prokaryote? Identify THREE distinctly different ecological roles that are played by prokaryotes in the marine environment. Briefly explain the importance of ONE of the above-identified roles.

Answer 4

A prokaryote is a unicellular organism without a nucleus.
Three distinctly ecological roles that are played by prokaryotes include chemoautotrophs, photoautotrophs and heterotrophs.
Photoautotrophs play an important role by contributing to about 90% of marine life’s primary food production.

Question 5

5. What is an autotroph? What is the main distinction between a chemosynthetic and a photosynthetic autotroph?
   Provide a specific example of a chemosynthetic marine organism. Where in the marine environment does this organism usually occur?
   Provide a specific example of a photosynthetic marine organism.
   Where in the marine environment does this organism usually occur?

Answer 5

An autotroph is an organism that is capable of producing its own food.
The main distinction between a chemosynthetic organism and a photosynthetic organism is that a chemosynthetic is able to form organic molecules from inorganic molecules using other chemicals rather than sunlight as a source of energy which is what a photosynthetic does.
Chemosynthetic organisms are bacteria, the bacteria usually shares a symbiotic relationship with invertebrates such as the Riftia Pachyptila, most commonly found around hydrothermal vents.
Algae is an example of a photosynthetic organism that uses light to fix co2, evolve o2. Algae is highly productive in shallow coastal waters,but most productivity is in the open ocean.

Question 6

6. Identify THREE major strategies used by sponges to reduce the impact or incidence of predation upon them. Briefly explain the basis of each of these strategies.

Answer 6

Sponges use three main strategies to counter predation & overgrowth. This includes physical characteristics, physical characteristics, asexual (colonial) reproduction, and chemical defence.
Physical characteristics include sponges having spicules and/or tough organic fibres. These features help deter predators directly (hard to digest, and could physically harm predators).
Asexual reproduction gives sponges an advantage as they can use cell division to replace damaged/missing body parts, many species can also generate a new colony from a small fragment.
Chemical defence occurs in sponges due to having a high incidence of biologically active compounds (toxic and/or anti-microbial effects). These compounds may be distasteful and/or toxic to a predator and therefore the predator will avoid the sponge.

Question 7

7. Outline the main types, diversity and general lifestyles of extant Cephalopoda.

Answer 7

There are over ~900 species of Cephalopoda that are exclusively marine, there are two main types - the Nautiloidea (nautilus & allies) and the Coleoidea (octopuses, squids, cuttlefishes & allies).
Cephalopoda are quite diverse.
Most Cephalopoda are found in the deep latitudes of the ocean within the cooler waters.

Question 8

8. For each of the following five specifications, provide the formal scientific name of an ANIMAL phylum that satisfies the specification. For each specification, select any phylum that satisfies that particular specification, except that you MUST use a DIFFERENT phylum for each specification.
   (i) Phylum that is exclusively marine.
   (ii) Phylum that is mainly marine (mostly marine species).
   (iii) Phylum that has been formally discovered only within the past ~50 years.
   (iv) Phylum that is mainly pelagic (mostly pelagic species).
   (v) Phylum that is mainly benthic (mostly with benthic species, at least as adults).

Answer 8

Phylum that is exclusively marine - Echinodermata (starfish)
Phylum that is mainly marine - Mollusca
Phylum that has been formally discovered only within the past ~50 years - Prochlorophytes (blue/green bacteria)
Phylum that is mainly pelagic - Arthropoda
Phylum that is mainly benthic - Porifera (sponges)

Question 9

9. What is a fish? What are the major groups (classes and subclasses) of fishes with living, marine representatives?

Answer 9

A fish is an aquatic vertebrate with gills and limbs in the shape of fins. All fishes are within the major phylum Chordata, classes include; Agnatha, Chondrichthyes, Holocephali, Elasmobranchii, Osteichtyes.

Question 10

10. What is Latimeria? What is the known geographic distribution and habitat of Latimera? Latimeria is often referred to as a ‘living fossil’ - explain why using specific details.

Answer 10

A Latimeria or 'Latimeria Chalumnae' is apart of the subclass Sarcopterygii also known as the only lobe-finned fish within the Coelacanth still living.
The distribution of of L. Chalumnae is not very wide spread, population is between ~200 to 500 individuals. 
The habitat of this fish is dermersal, it's found near steep rocky slopes with caves & overhangs, the depths range between ~100-700m.
The Latimeria is often referred to as a 'living fossil' due to fossils of this species dating back to ~410 MYA, long before the age of the dinosaurs. Initially Coelacanths were known from the fossil record, in 1938 a recently dead specimen from Western Indian Ocean was discovered. Since 1938 more research was conducted and more of this species was found, hence Latimeria known as the 'living fossil'

Question 11

11. Name FIVE fundamental body shapes found in bony fishes. Provide a specific example of a bony fish with each of these body shapes. Indicate the type(s) of lifestyle that is generally said to be associated with each of these body shapes.

Answer 11

1) Fusiform - example: Marlin, tuna
Lifestyle: active swimmers

2) Flattened - example: flounder, flathead
Lifestyle: hug bottom

3) Globular - example: anglerfish, boxfish
Lifestyle: sedentary

4) deep, laterally compressed - example: butterfly fish
Lifestyle : navigate large obstacles

5) ‘snake-like’ - example: eels
Lifestyle: lives in burrows or tight spaces.

Question 12

12. What is a mangrove? Identify, with precise details, FOUR environmental factors that determine the distribution of mangroves.

Answer 12

Mangroves are intertidal, salt tolerant, trees and shrubs.
Four environmental factors that determine the distribution of mangroves includes : the salinity, warm waters, intertidal, protected waters.
Mangroves require salt water in order to thrive, they also hold many adaptations for such saline environments to control inputs and outputs.
Warm waters are required >20c (average) to grow and populate.
Mangroves also need to be intertidal to gain the consistent substances it need to thrive such as water and salt.
Mangroves also have unstable root system, limited wave action is required.

Question 13

13. Identify FOUR ‘adaptations’ of sea grasses to sub tidal environments. Briefly explain the significance of each of these ‘adaptations’.

Answer 13

Four adaptations of sea grasses include:
Thin cuticle son the leaves, this means there’s very little or no stomata so it does not require a lot of sunlight.
Leaf sheaths help protect the diffusion and absorption of salt.
Sea grass is made of strong fibres for strength against currents and wave action.
Sea grass contains a rhizome system which helps the sea grass anchor itself in soft sediment.

Question 14

14. True sea snakes (Family Hydrophiidae) have a range of characteristics that facilitate dives of long duration. Identify FOUR such characteristics. Briefly explain the significance of each of these four characteristics.

Answer 14

Four characteristics include;
Cutaneous respiration - which is when gas exchange happens through the skin such as sea snakes underwater.
Water tight valves - that seal the snakes nostrils when diving to prevent water entering the lungs.
Sea snakes have a large, single, long lung - which supply’s good oxygen storing capacity.
Cardiac shunt - which means they can direct blood to different parts of the body, this can help maximise the snakes dive but helping nitrogen blood levels stay low enough to not be harmful to the snake.

Question 15

15. What is a sea bird? Name ONE of the major taxa (orders) of seabird and describe the main characteristics and range of types of the seabirds within the named taxon.

Answer 15

A seabird is a bird that obtains their food from the sea, little difference between seabirds and shorebirds.
One major taxa includes Charadiiformes.
Characteristics include small to medium size (~25 to 2kg), open nostrils, mainly coastal, found worldwide, most are in the northern hemisphere.
Examples: sea gulls, terns, noddles,skimmers, alcids,skuas,shorebirds.

Question 16

16. Alicids (auks, puffins, and murres) and penguins share a range of general morphological characteristics that are believed to be due to convergent evolution. Identify FIVE such characteristics. For each of the identified characteristics, indicate the selective pressure(s) that most likely generated the convergence.

Answer 16

Black and white colour - s.p. Would be predation, as well as a potential tactic to catch prey by a counter shading camouflage pattern.
Webbed feet - s.p. For swimming, ability to be agile and quick in the water.
Stiff-board beak - use of a weapon/tool to catch prey
Torpedo shaped body - aerodynamic design forced to help them dive deeper/propel through water fluently.
Dense, overlapping feathers - for insulation, prevent heat loss and waterproofing the body to keep them dry and warm in cold temperatures.

Question 17

17. Outline the taxonomic range of marine mammals.

Answer 17

~125 marine species

Three main groups: Carnivora, Sirenia, Cetace.

Question 18

18. Marine mammals have evolved a range of characteristics that help them retain heat in cold water. Identify FOUR such characteristics. Briefly explain the significance of each of these four characteristics.

Answer 18

Large body size - a large body provides less surface area per unit volume over which to lose heat, it allows thicker insulation.
Insulation: blubber - blubber is a dense, vascularised layer of fat reinforced by collagen and elastic fibres, it functions as an insulator because it’s poor conductor of heat.
Insulation: fur - fur functions as an insulator by trapping pockets of air among the hairs (air is a poor conductor of heat), but fur is more effective insulator than blubber in air.
Counter-current heat exchange - cold blood from the extremities in the veins runs next to warm blood flowing to the extremities in the arteries, heat is transferred from the arterial blood to the venous blood reducing heat loss in the extremities.

Question 19

19. Outline the life cycle of the Western Rock Lobster, Panulirus cygnus AND critically evaluate the claim that the Western Rock Lobster is a benthic organism.

Answer 19

1) larval stage - planktonic ~9 months
2) Postlarval stage - nektonic ~2 weeks
3) juveniles & adults - benthic ~20+ years

The western rock lobster is a benthic organism as during its larvae stage it could be considered as a pelagic organism but during its juvenile/ adult life it will spend a large proportion of its life span on the shallow reefs, and on the sea floor.

Question 20

20. Phytoplankton are often small in size and irregular in shape.
    (I) Define the term ‘phytoplankton’.
    (ii) Identify and briefly explain TWO advantages that phytoplankton obtain by being small in size and irregular in shape.

Answer 20

Phytoplankton is photosynthetic plankton (prokaryotes & eukaryotes).
One advantage to being small is that you are relatively influenced by vicous forces hence you tend to sink relatively slowly - this results in less energy to maintain a position.
Having an irregular shape as well as a small size also shows that the organism will have a high sa:v ratio which contributes to drag and non-linear sinking patterns, this also means less energy use and less predation along bottom dwelling scavengers.

Question 21

21. Distinguish between holoplanktonic and meroplanktonic organisms. Provide the formal scientific and common names of THREE holoplanktonic species and of THREE meroplanktonic species.

Answer 21

Holoplanktonic- species that spend their entire life cycle in plankton.
Meroplanktonic- only spend part of their life cycle in plankton (typically larvae and eggs)

Meroplanktonic -
black-lip abalone
Blue swimmer crab
Western rock lobster

Holoplanktonic -
Krill
Copepods
Amphipods

Question 22

22. What is counter shading? Provide a specific example of an epipelagic organism that exhibits countershading. Briefly explain how countershading provides camouflage in epipelagic environments. What are photophores? Provide a specific example of a mesopelagic organism that has photophores. Briefly explain explain how photophores can provide camouflage in mesopelagic environments.

Answer 22

Counter shading is a camouflage pattern used to counter the colour of its surroundings.
An example of an organism is the Gentoo Penguin.
Counter shading provides camouflage by the upper surface of pelagic animals is dark and the lower surface light to blend in with the ocean depths or the surface, hence more difficult for predators to see its prey.
A photophore is a specialised organ in some organisms that produces bioluminescence.
An example of an organism is the lantern fish. The lantern fish camouflages by counter-shading black and silver with elaborate photophores to help create the silver effect in the dark depths to produce light.

Question 23

23. Fishes that live below the euphoric zone have a range of characteristics that facilitate their survival in food-limited environments. Outline FOUR such characteristics. Briefly explain how each of these characteristics facilitates survival in food-limited environments.

Answer 23

• good swimmers
• usually streamline
• vision is well developed- good in active pursuits
• counter shade

Question 24

24. What are kelps? What are kelp forests? Where in the marine environment do kelp forests occur? Briefly outline the ecological significance of kelp forests.

Answer 24

Kelp is usually defined as large brown algae.
A kelp forest is simply a dense assemblage of kelp, algae from a surface canopy.
Kelp forests usually occur in shallow, colder waters, high water motion.
The significance of kelp forests are a food source for animals, primary producers of detritus - based food webs.

Question 25

25. Distinguish between hard and sedimentary substrates (in the context of benthic, marine environments). What types of invertebrates typically dominate hard substrates? What types of invertebrates typically dominate in sedimentary substrates?

Answer 25

Hard substrate: any solid substrate e.g rock, wood, hard surface.
Invertebrates: kelp forests, pier pilings, macro organisms, suspension feeders, sponges,

Sedimentary substrate: mix of inorganic and organic particles and pure water - e.g gravel, sand, mud
Invertebrates: crustaceans, bivalves, polyohaetes, holothurians

Question 26

26. (i) what is plankton?
    (ii) indicate the major taxonomic groups that are commonly represented in marine plankton.
    (iii) Outline the tropic role(s) of marine plankton.

Answer 26

Plankton are organisms living in the water column that are unable to maintain their position against water currents.
Major taxonomic groups represented in prokaryotes, fungi, protists, plants & animals.
General trophic role (phytoplankton & zooplankton) - primary producers at high latitudes, maximise species diversity and abundance at low latitudes, primary producers in nutrient poor area.

Question 27

27. (i) what is nekton?
    (ii) indicate the major taxonomic groups that are commonly represented in marine nekton.
    (iii) outline the trophic role(s) of marine nekton.

Answer 27

A nekton is organisms living in the water column with swimming abilities that allow them to move actively through the water and against currents.
The major taxonomic groups are vertebrates (both primary and secondary) marine vertebrates, also includes pelagic cephalopods plus a range of other invertebrates that are ‘borderline’ between nekton and plankton.
Nekton trophic role are composed of consumers - mainly carnivores and predators (upper levels of the food chain).

Question 28

28. (i) what are benthos?
    (ii) indicate the major taxonomic groups that are commonly represented in marine benthos.
    (iii) Outline the trophic role(s) of marine benthos.

Answer 28

Benthos are organisms living on the seabed, major groups include kelp forests, pier pilings, algae, macro invertebrates.
Trophic role most primary production within the detritus - based food webs.

Question 29

29. Discuss why Antarctic Krill (euphasia superba) is thought to play a special role in Antarctic waters.

Answer 29

The Antarctic krill are a vital link in our marine food webs.
Dominant zooplankton within Antarctic waters covers up to 125- 725 million tonnes.
Vital component of Antarctic food webs, virtually all larger consumers rely directly or indirectly on krill.
Krill is known to be a keystone species - that means that the species can have a great impact on its community, if removed it could drastically alter many species abundance and overall environment.
The Antarctic communities are quite ‘simple’ food webs, keystone species are most found in simple webs.

Question 30

30. Within the past ~40 years, there have been a few discoveries that have resulted in MAJOR changes to scientific views about the biological structure and/or function of marine systems.
    (i) Identify ONE such discovery.
    (ii) Briefly explain the main ways in which this discovery has altered scientific views about the biological structure and/or function of marine systems.

Answer 30

In 1977, scientists discovered deep sea hydrothermal vents where many new species were thriving near the Galapagos rift along the mid-ocean ridge in the eastern pacific.

This discovery made scientists wonder how deep the ocean temps could change so drastically from near freezing to 400c in such a short distance, they then discovered hydrothermal vents. They also discovered an entirely unique ecosystem that existed around the vents. Despite these extreme temps, toxic minerals, and lack of sunlight, species there were thriving. Scientists saw bacteria were converting toxic minerals into usable forms of energy through chemosynthesis, providing food for the other organisms.
This discovery has hence altered and redefined our understanding of the requirements for life to thrive.
The ability for organisms to survive and thrive in extreme temp, toxic substances proves an astonishing discovery that would change the way we think of life forever and how complex life really is.