Study Marine Studies II from home

This course follows on from Marine studies I, extending your knowledge of a wide variety of marine organisms. It works through many types of marine organisms, focusing mostly on those not covered as well in Marine Studies II (This includes: Protists, Sponges, Marine plants, Cnidarians, Worms, Arthropods, Molluscs, Echinoderms, Non Bony Fish, Selected Bony Fish and selected Marine Mammals).

Expand your knowledge of Fish and other Marine Life

  • Work in marine industries, conservation, diving, exploration, resources, tourism, etc.
  • 100 hour, self paced study, building on Marine Studies I

There are 10 lessons as follows:

  1. Introduction and Simple Organisms (Protists, Sponges etc)
  2. Marine Plants
  3. Cnidarians and Worms:
    1. Anemones
    2. Jellyfish
    3. Crustaceans
    4. Flatworms
  4. Arthropods
  5. Molluscs
  6. Echinoderms:
    1. Starfish
    2. Sea Urchins
    3. Sea Cucumbers
  7. Non-Bony Fishes:
    1. Lampreys
    2. Hagfishes
    3. Sharks
    4. Rays
  8. Bony Fishes I
  9. Bony Fishes II
  10. Marine Mammals

Each lesson culminates in an assignment which is submitted to the school, marked by the school's tutors and returned to you with any relevant suggestions, comments, and if necessary, extra reading.


  • Describe the variety and nature of microscopic animals which occur in marine environments.
  • Describe the variety and nature of a range of different types of marine plants.
  • Describe the variety and nature of a range of different types of cnidarians and marine worms.
  • Describe the variety and nature of arthropods in marine environments.
  • Describe the variety and nature of Molluscs in marine environments.
  • Differentiate between different classes of Echinoderms and selected families within those classes.
  • Describe the shared characteristics and distinguishing features of a selection of different species of non-bony fish.
  • Describe characteristics of bony fish, including anatomy, physiology and behaviour.
  • Differentiate between different families of bony fish.
  • Describe the taxonomic characteristics of groups of marine animals including reptiles, birds and mammals.

You will engage in a variety of learning activities through a combination of reading, interacting with tutors, undertaking research and practical tasks, and watching videos. Some of these activities are:

  • Draw a table to compare three different phyla of marine protists.
  • Explain the differences between sponges, krill and plankton.
  • Produce a table that compares the characteristics of the three different types of algae.
  • Explain the difference between seaweed and sea grass.
  • How important are marine plants to the survival of marine animals?
  • Explain features that distinguish different types of worms apart, including:
    • Flatworms
    • Ribbon Worms
    • Segmented Worms
    • Peanut Worms
  • Present a report on research on the Cnidarians.
  • Explain the formation of coral reefs. Why are they considered one of the most biologically productive environments.
  • Explain the advantages of the arthropod's body structure compared to the structure of the less complex animals studied so far in this course.
  • Research the living environments of one local arthropod and consider how its body structure and feeding mechanism are adapted to its environment.
  • Discuss limitations in lifestyle and behaviour might be imposed by the structure of arthropods.
  • Differentiate between cephalopods, gastropods and bivalves.
  • Describe the feeding and defence mechanisms of two different molluscs.
  • Describe the advantages and disadvantages of the echinoderm's radially symmetrical body.
  • Describe the feeding, breeding and defence characteristics of echinoderms.
  • Select 3 echinoderms and describe their method of reproduction.
  • Describe the sensory and behavioural adaptations that sharks and rays use for defence and feeding.
  • Discuss whether sharks deserve their reputation as maneaters.
  • Explain the the main differences between sharks and rays, and the main benefits to these creatures of these differences.
  • Describe the relationship between a particular kind of lamprey (ideally, one found locally) and its host, considering who benefits and/or who does not, and why.
  • List three families of local bony fish.
  • Briefly describe the biological characteristics of three fish families:
    • structure
    • feeding
    • colouration
    • reproductive
    • defence mechanisms
  • Discuss the behavioural characteristics of the three families you researched:
    • territorial behaviour
    • migration
    • schooling
    • reproductive behaviour
  • Draw and describe the gills of bony fish, and explain their function.
  • Identify families of fish characterised by their habit of sitting perched on their lower fins.
  • Describe special adaptations of fish and other marine organisms that live in the mid to deep zones of the ocean.
  • List the most significant bony fish that occur in your nearest marine waters, and briefly describe their marine environment.
  • Research in detail 1 marine reptile and 2 marine mammals.


  • Plan your study program. Allocate certain times for study and stick to these. 
  • Use Active Reading Techniques - keep in mind what the purpose of reading is. 
  • Find a quiet place to study - allocate a room away from the busy areas of the house for study.
  • Make the most of the set tasks – these are a great way to apply what you have learnt in a practical way.


What Do You Know about Bony Fish?

All bony fish fall within the Class Osteichthyes. Bony fishes have evolved the most complex head skeleton of all other classes, with complete dermal (skin) skeletons of small to medium size bones (scales). They have internal gills in one chamber that are protected by a bony operculum.

The internal skeleton is composed, at least partly, of true bones. Fins have rays, sometimes they are spiny. Most species have a swim bladder. The salt and water balance is maintained by kidneys. Fish of this class inhabit both seas and fresh waters and many species migrate between seas and rivers in their life cycle. 

This group has enormous commercial importance around the world.  It is the largest class of vertebrates. Of the 25,000 fish species most are bony. Ninety eight percent of all fishes are bony – this is almost half of all vertebrates! Between 75 and 100 new species are described every year.

The body shape of bony fish will vary depending on its lifestyle. Fast swimming fish (eg. Tuna, Marlin, and Mackerel) have streamlined bodies. Laterally compressed bodies are better for swimming around kelp beds or reefs. Flat bodies (eg. Flounder) are ideal for living on the bottom of the sea bed.

Body shape may also help with camouflage (eg. Pipefish live in sea grass which has a similar shape to the fish’s body). Slow moving fish (eg. Blennies and Sculpins) have irregular growths on body that contribute to camouflage.

Colour is often used for camouflage, particularly in tropical species. Deep water fish often use colour for camouflage. Many fish can rapidly change colour by contracting or expanding pigment in special cells called chromatophores. Some chromatophores contain special crystals that reflect light giving the fish’s surface a shiny appearance.

Colour change may be for any of several reasons, including camouflage, mood or reproduction as examples. Open water fish and shallow water predators are rarely very colourful.

Bony fish have a swim bladder that provides buoyancy. Cartilaginous fish do not have this bladder, hence they need to use pectoral fins to provide lift as well as thrust. They generally have greater maneuverability than cartilaginous fish.

There are two types of swim bladders in bony fish, open or closed. Most of the primitive fish such as salmon, herring and eels have an open swim bladder. There is a connecting tube from the swim bladder to the oesophagus. These species fill the bladder by swallowing air at the water surface. This method of buoyancy can provide difficulties to fish that swim at greater depths as the water pressure increases the swim bladder will shrink on descent.

Most bony fish have the closed swim bladder. This bladder is not connected to the gut. Swim bladders generally take up about 5% of the body mass. This small size allows for neutral buoyancy. The swim bladder can also function as a receptor and producer of sound. It can help the fish to discriminate between a wider range of frequencies and decipher pitch better than the otolith of the ear.