Life in the Sea 



CLASSIFICATION OF MARINE 

 PLANTS 



This subject is complex and still under 

 discussion; the following sets out what 

 is currently accepted: 



SCHIZOPHYTA 



Bacteria 

 Blue-green algae 



RHODOPHYTA 



Red algae 



PYRROPHYTA 



Dinoflagellates 



CHRYSOPHYTA 



Yellow-green algae 

 Diatonns 



PHAEOPHYTA 



Brown algae 



CHLOROPHYTA 



Green algae 



FUNGI 

 CORMOPHYTA 



ANGIOSPERMS: There are about 30 species of 

 these flowering plants present in the sea. They did 

 not originate in the sea but have colonized it by 

 way of fresh water. They are found mainly in estu- 

 aries or in water of low salinity. 



MARINE PHYTOPLANKTON consists of micro- 

 scopic members of the divisions PYRROPHYTA, 

 CHRYSOPHYTA, and CHLOROPHYTA. Its chief 

 constituents are dinoflagellates, yellow-green 

 algae, especially coccollthophores, and diatoms. 



CLASSIFICATION OF MARINE 

 ANIMALS 



Phylum PROTOZOA 



Mastigophora - dinoflagellata 



Sarcodina - foraminifera 



Actinopoda - radiolaria 



Ciliata 



PARAZOA (Sponges) 



Phylum COELENTERATA 



Hydrozoa - hydroids and medusae 

 Scyphozoa - jellyfishes 



Anthozoa - Subclass Alcyonaria 

 includes black corals, sea fans, 

 gorgonia, and sea pens. Subclass 

 Zoantharia includes sea anemones, 

 true corals, and stony corals. 



Phylum CTENOPHORA 



comb jellies 



Phylum PLATYHELMINTHES 



flatworms 



Phylum NEMATHELMINTHES 



roundworms 



Phylum TROCHELMINTHES 



Rotifera - wheel animalcules 

 Kinorhyncha 



Phylum POLYZOAorBRYOZOA 



moss animals 



Phylum BRACHIOPODA 



lamp shells 



Phylum CHAETOGNATHA 



arrow worms 



Phylum ANNELIDA 



true or ring worms 

 Phylum MOLLUSCA 



Amphineura - chitons 

 Gastropoda - many with spiral shells, 

 and limpets. 



Scaphopoda - tusk shells 

 Pelecypoda (Bivalvia) - mussels, 

 scallops, oysters, and clams. 

 Cephalopoda - squid, octopus, 

 cuttlefish, and nautilus. 



Phylum ARTHROPODA 



Crustacea - includes Ostracoda, 

 Copepoda, Cirripedia (barnacles). 

 Malacostraca - includes Euphausiacea 



(krill), prawns, lobsters, crayfish, 

 crabs (the last four being known as 

 decapod Crustacea). 

 Pycnogonida (sea spiders) 

 Insecta 



Phylum ECHINODERMATA 



Holothuroidea (sea cucumbers) 

 Echinoidea (sea urchins) 

 Asteroidea (starfishes) 

 Ophiuroidea (brittle stars) 

 Crinoidea (sea lilies, feather stars). 



Phylum CHORDATA 



Pogonophora - beard worms 



Phoronida 



Ascidiacea - sea squirts 



Thaliacea - includes salps 



Larvacea 



Enteropneusta 



Pterobranchia 



Cephalochordata (amphioxus or 



Branchiostoma) 



Subphylum vertebrata 



Cyclostomata - lampreys, hag fishes. 

 Euselachii - sharks, dogfishes, angel- 

 fishes, skates, and rays. 

 Bradyodonti - rabbit fishes 

 Pisces - true or bony fishes 

 Crossopterygli - coelacanth and 

 lung fishes. 



Reptilia - sea snakes and turtles. 

 Aves - few birds are truly marine, 

 but some are dependent on the sea 

 for food. 



Mammalia - Cetacea include whales, 

 dolphins, and porpoises; Pinnipedia 

 include walrus, sea lions, and seals; 

 Sirenia include dugong and manatee. 



ZOOPLANKTON includes all of the animals 

 which drift about passively with the currents, as 

 distinct from those animals which can make ex- 

 tensive movements and migrations by their own 

 efforts. It is composed of many groups of animals 

 including Protozoa, smaller Crustacea, Medusae, 

 Fishes, Molluscs, and the eggs and larvae of many 

 other groups. 



Zones of Marine Environment 



The marine environment can be divided 

 into several ecological zones 

 based on physical-chemical factors, 

 or the nature of the fauna and flora. 

 While the boundary between the zones 

 may sometimes be well defined, 

 usually there is overlapping because 

 the zones are interdependent. The 

 organisms in a deep trench, for 

 instance, are dependent on biological 

 conditions of the overlying water 

 masses up to the very surface, 

 where the primary production of 

 organic matter takes place. The two 

 primary zones of the sea are the 

 "photic" and "aphotic." In the photic 

 zone light is the dominant factor 

 during the day. In the aphotic 

 zone there is virtually no light. 



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