11. Protochordata
Protochordates are also known as tunicates due to the thick mantle that
surrounds their body. Secreted from the skin, this cuticle is similar to
connective tissue and contains fibrous material; some species lack a cuticle,
possessing a transparent, agar-like membrane. Organisms live independent
or in colonies. Those that live in colonies have large, egg-shaped bodies
with rootlike appendages at the bottom to attach to other objects. The most
representative protochordates are sea squirts.
12. Vertebrata
Vertebrates are animals that possess a backbone. Fish are considered the
chief example of marine vertebrates.
Fish live primarily in the water and propagate by laying eggs. They use
gills to breathe, their body temperature varies with the surrounding environment, and their bodies are covered with scales. Fish have streamlined
body shapes to allow them to swim with little resistance from the water.
Over 2500 species of fish are known to exist around the world.
(2) Marine Plants
The term “seaweed” or “marine algae” is used to refer to plants that inhabit the
sea and perform photosynthesis. Also included in this category are floating
microalgae, including phytoplankton, sea grass, and blue-green algae. Typically, the term seaweed refers to sessile cryptogams. Like land-based plants,
algae perform photosynthesis, but because they inhabit saline seawater, they
absorb nutrients through their entire bodies. Their metabolites also differ from
those of land-based plants and are important sources of natural substances.
Phytoplankton in particular is a primary producer of various bioactive substances and can be easily cultured within the laboratory.
Around 25,000 species of algae exist worldwide. Over 600 inhabit the Korean
coast, including 80 species of green algae, 135 of brown algae, 355 of red
algae, and 48 of blue-green algae.
(3) Marine Microorganisms
Marine microorganisms possess completely different characteristics from
land-based microorganisms and exist in halophile, halotolerant, psychrophile,
pressure-resistant, and barophile types. These properties must be taken into
account when searching for and culturing marine microorganisms. When
bioactive substances are being isolated from microorganisms, the organisms
must first be separated out and mass-cultured, after which the active substances are isolated and refined. The process thus requires separate microorganism isolation and culturing techniques.
The biggest advantage to microorganisms is that they possess few impurities
within their bodies, which makes isolation and refinement of substances a
relatively simple process. Care must be taken during culturing, however, as
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351
Protochordates are also known as tunicates due to the thick mantle that
surrounds their body. Secreted from the skin, this cuticle is similar to
connective tissue and contains fibrous material; some species lack a cuticle,
possessing a transparent, agar-like membrane. Organisms live independent
or in colonies. Those that live in colonies have large, egg-shaped bodies
with rootlike appendages at the bottom to attach to other objects. The most
representative protochordates are sea squirts.
12. Vertebrata
Vertebrates are animals that possess a backbone. Fish are considered the
chief example of marine vertebrates.
Fish live primarily in the water and propagate by laying eggs. They use
gills to breathe, their body temperature varies with the surrounding environment, and their bodies are covered with scales. Fish have streamlined
body shapes to allow them to swim with little resistance from the water.
Over 2500 species of fish are known to exist around the world.
(2) Marine Plants
The term “seaweed” or “marine algae” is used to refer to plants that inhabit the
sea and perform photosynthesis. Also included in this category are floating
microalgae, including phytoplankton, sea grass, and blue-green algae. Typically, the term seaweed refers to sessile cryptogams. Like land-based plants,
algae perform photosynthesis, but because they inhabit saline seawater, they
absorb nutrients through their entire bodies. Their metabolites also differ from
those of land-based plants and are important sources of natural substances.
Phytoplankton in particular is a primary producer of various bioactive substances and can be easily cultured within the laboratory.
Around 25,000 species of algae exist worldwide. Over 600 inhabit the Korean
coast, including 80 species of green algae, 135 of brown algae, 355 of red
algae, and 48 of blue-green algae.
(3) Marine Microorganisms
Marine microorganisms possess completely different characteristics from
land-based microorganisms and exist in halophile, halotolerant, psychrophile,
pressure-resistant, and barophile types. These properties must be taken into
account when searching for and culturing marine microorganisms. When
bioactive substances are being isolated from microorganisms, the organisms
must first be separated out and mass-cultured, after which the active substances are isolated and refined. The process thus requires separate microorganism isolation and culturing techniques.
The biggest advantage to microorganisms is that they possess few impurities
within their bodies, which makes isolation and refinement of substances a
relatively simple process. Care must be taken during culturing, however, as
10.2 Researching Natural Marine Substances
351