Biological Classification

The diversity of marine life

The ocean is home to a wide variety of organisms

Marine organisms range from microscopic bacteria and algae to the largest animal in the world (blue whale)

Number of known marine species: 250,000

Classification of living things

Organisms can be classified into one of three domains of life:

Archaea

Bacteria

Eukarya

Classification of living things

Organisms can also be classified into one of five kingdoms:

MoneraProtoctista (Protista)FungiPlantaeAnimalia

Classification of living things

Taxonomic classification includes the following increasingly specific groupings:

KingdomPhylum (Division for plants)ClassOrderFamilyGenusSpecies

Taxonomic classification of selected organisms

Category Human Killer whale Giant kelp

Kingdom Animalia Animalia Protoctista

Phylum Chordata Chordata Phaeophyta

Subphylum Vertebrata Vertebrata

Class Mammalia Mammalia Phaeophycae

Order Primates Cetacea Laminariales

Family Hominidae Delphinidae Lessoniaceae

Genus Homo Orcinus Macrocystis

Species sapiens orca pyrifera

Classification of marine organisms

Marine organisms can be classified into one of three groups based on habitat and mobility:

1. Plankton (floaters)Phytoplankton (drifting plants and algae)Zooplankton (drifting animals)

2. Nekton (swimmers)3. Benthos (bottom dwellers)

Plankton: Examples

Phytoplankton Zooplankton

Nekton: Examples

Benthos: Examples

Life cycle of a squid

Squid experience benthic, planktonic, and nektonic stages

Squid are considered meroplankton (opposite = holoplankton)

Distribution of species on Earth

The land has more species because it has greater environmental variability than the ocean

Most ocean species are benthic because of greater environmental variability compared to pelagic environments

Zones in the Ocean

Divisions of the marine environmentMain divisions:

Pelagic (open sea)

Benthic

(sea bottom)