Organism Categories and Pages
The categories below are loosely based on phylum or similar groups, increasing with complexity towardss the bottom. Several are convenience groups only.
These single-celled producers of energy are golden-brown unlike the green producers in freshwater. Diatoms are a major part of the phytoplankton. A different, algal producer is here, too, Halosphaera, which is green.
These are the second main component of phytoplankton, although some do not photosynthesise and are predatory. Some are both. They are varied in structure, shape and size, even toxic. Phaeocystis although not a dino is here too.
This section follows the dinos that are also protists, a hugely varied group of single-celled organisms. The ciliates are particularly complex and intriguing group that include the Tintinnids. Radiolaria is an especially beautiful group.
The Foraminifera, often shortened to Forams, typically live in sediment or on the rocky shore. Only a limited number have a planktonic life but they are easily disturbed, e.g. rough weather, and enter the plankton. They are essentially a shelled amoeba!
Cnidarians and Ctenophores. These two phyla are a major part of the gelatinous zooplankton: larvae of sea anemones, hydroid medusae, Siphonophores (planktonic hydroids) and jellyfish larvae. Comb Jelly and Sea Gooseberry are common Ctenophore names.
Many creatures are called worms but the only true marine ones are the polychaetes. This category covers slightly obscure organisms; The Ribbon Worms (Nemertea), the Arrow Worms (Chaetognatha) and the Acorn Worms (Hemichordata)
There are many tiny little flatworms active in the plankton as well as larval forms like the Muller larvae. Trematodes are parasitic flatworms that use the plankton to disperse between hosts. Other parasites are here including crustacean forms.
These are the true marine worms characterised by having bristles called chaetae. A few live permanently within the zooplankton while many more have a series of planktonic larval forms, most amazingly beautiful. Some have strange life cycles
Although there are snails that live permanently in oceanic plankton they are very rare on our coast. Larval forms of our shore species like periwinkles can be abundant as are those of bivalves like cockles.
Copepods and Cladocerans. These crustaceans are permanent member sof the zooplankton living their entire lives in the plankton. Cladocera are the water fleas that are common in freshwater but have a more limited marine presence.
Other than the Cumacea, most in this section are larval forms of shore animals like barnacles, decapods (crabs and shrimps), mysids (the opossum shrimps) and isopods. There is even an amphipod that moves between jellyfish.
Colonies of Sea Mats, tiny animals covering seaweeds and hard substrates are derived from a single larva landing from the plankton. Cyphonautes are the most common larva as they remain pelagic for weeks unlike the coronate form. Phoronids are a different phylum but the adults share some similarity.
This phylum constitute small creatures, 400-500 microns, found in most water environments. Marine ones are not so diverse as freshwater and dominated by the genus Synchaeta
Most starfish, brittlestars, sea urchins and sea cucumbers have quite spectacular larval stages, some multiple phases. There are similarities within the phylum but larvae vary considerably.
The larvae of sea squirts and ascidians, like elongated tadpoles, are found in the plankton but the Appendicularians, notably the species Oikopleura, live permanently pelagic lives
Non-seashore fish, like sand eels, can produce huge numbers of eggs that are released into the plankton. Once hatched the larva will feed on zooplankton.
Every plankton sample collected will have some mysterious structure or organism present that can take months or longer to identify. Some are initially strange, like pollen, but with so much being released it is inevitable that some will be caught in the sea
