Plankton: microscopic giants 
Hydromedusa
Taxa: Eucheilota paradoxica
Size: 1.0 - 10 mm
Place: Canal de São Sebastião, São Sebastião, SP, Brazil
Tags: cebimar-usp, dark-field, adult, planktonic
Hydroid and hydromedusa
Newly released medusa.
Taxa: Hebella furax
Size: 0.1 - 1.0 mm
Place: Saco Grande, São Sebastião, SP, Brazil
Tags: jellyfish, benthic, cebimar-usp, dark-field, planktonic, epibiotic, rocky-shore
Chaetognath
Taxa: Flaccisagitta enflata
Size: 1.0 - 10 mm
Place: Canal de São Sebastião, São Sebastião, SP, Brazil
Tags: cebimar-usp, dark-field, adult, planktonic
Tintinnid with hyaline lorica
Taxa: Ascampbelliella aperta
Size: <0.1 mm
Place: Canal de São Sebastião, São Sebastião, SP, Brazil
Tags: unicellular, cebimar-usp, dic, planktonic
Pluteus larva of a sea biscuit
Taxa: Clypeaster subdepressus
Size: 0.1 - 1.0 mm
Place: São Sebastião, SP, Brazil
Tags: larva, confocal, planktotrophic, planktonic
Pluteus larva of a sea biscuit
Larva with six arms.
Taxa: Clypeaster subdepressus
Size: 0.1 - 1.0 mm
Place: CEBIMar, São Sebastião, SP, Brazil
Tags: larva, dark-field, planktotrophic, planktonic
Parasitized copepod
Taxon: Acartia, Isopoda
Size: 0.1 - 1.0 mm
Place: Canal de São Sebastião, São Sebastião, SP, Brazil
Tags: cebimar-usp, dark-field, adult, parasite, planktonic
Copepod
Taxa: Copilia mirabilis
Size: 0.1 - 1.0 mm
Place: Canal de São Sebastião, São Sebastião, SP, Brazil
Tags: cebimar-usp, dark-field, adult, planktonic
Copepod
Taxa: Acartia lilljeborgii
Size: 0.1 - 1.0 mm
Place: Canal de São Sebastião, São Sebastião, SP, Brazil
Tags: cebimar-usp, dark-field, adult, planktonic
Heteropod - marine free-swimming gastropod
Taxa: Atlanta peronii
Size: 0.1 - 1.0 mm
Place: Canal de São Sebastião, São Sebastião, SP, Brazil
Tags: cebimar-usp, dic, adult, planktonic
Pteropod mollusk
Taxa: Limacina lesueuri
Size: 0.1 - 1.0 mm
Place: Canal de São Sebastião, São Sebastião, SP, Brazil
Tags: cebimar-usp, dark-field, adult, planktonic
Plankton
Overview of a sample of plankton in a stereomicroscope.
Size: 0.1 - 1.0 mm
Place: Canal de São Sebastião, São Sebastião, SP, Brazil
Tags: cebimar-usp, dark-field, planktonic
Dinoflagelate
Taxa: Protoperidinium
Size: <0.1 mm
Place: Canal de São Sebastião, São Sebastião, SP, Brazil
Tags: unicellular, cebimar-usp, planktonic, bright-field
Hydromedusa
Taxa: Corymorpha bigelowi
Size: 1.0 - 10 mm
Place: Shiharama, Wakayama, Japan
Tags: jellyfish, macrophotography, seto marine biological laboratory, planktonic, cnidarian tree of life project
Larva
Taxa: Magelonidae
Size: 0.1 - 1.0 mm
Place: Canal de São Sebastião, São Sebastião, SP, Brazil
Tags: larva, cebimar-usp, dark-field, planktotrophic, planktonic
Hydromedusa
Newly released medusa.
Taxa: Ectopleura obypa
Size: 0.1 - 1.0 mm
Place: CEBIMar, São Sebastião, SP, Brazil
Tags: jellyfish, cebimar-usp, dic, planktonic
Larva
Taxa: Polynoidae
Place: Canal de São Sebastião, São Sebastião, SP, Brazil
Tags: larva, cebimar-usp, dark-field, planktotrophic, planktonic
Scyphozoan
Taxa: Chrysaora lactea
Size: >100 mm
Place: Canal de São Sebastião, São Sebastião, SP, Brazil
Tags: jellyfish, cebimar-usp, adult, planktonic
Scyphozoan
Medusa.
Taxa: Phyllorhiza punctata
Size: 10 - 100 mm
Place: Canal de São Sebastião, São Sebastião, SP, Brazil
Tags: jellyfish, macrophotography, cebimar-usp, adult, planktonic
Newly released medusa
Taxa: Clytia linearis
Size: 1.0 - 10 mm
Place: Pier Petrobras, São Sebastião, SP, Brazil
Tags: benthic, cebimar-usp, dark-field
Hydromedusa
Taxa: Aequorea
Size: 10 - 100 mm
Place: Canal de São Sebastião, São Sebastião, SP, Brazil
Tags: jellyfish, macrophotography, cebimar-usp, adult, planktonic
Plankton
Overview of a sample of plankton in a stereomicroscope.
Size: 0.1 - 1.0 mm
Place: Canal de São Sebastião, São Sebastião, SP, Brazil
Tags: cebimar-usp, dark-field, planktonic
Holoplanktonic polychaete
Taxa: Tomopteris
Size: 1.0 - 10 mm
Place: Canal de São Sebastião, São Sebastião, SP, Brazil
Tags: cebimar-usp, dark-field, adult, planktonic
Bryozoan coronate larva
Taxa: Watersipora subtorquata
Size: 0.1 - 1.0 mm
Place: Ponta do Jarobá, São Sebastião, SP, Brazil
Tags: larva, lecithotrophic, cebimar-usp, dic, planktonic
Copepod
Taxa: Macrosetella gracilis
Size: 0.1 - 1.0 mm
Place: Canal de São Sebastião, São Sebastião, SP, Brazil
Tags: cebimar-usp, dark-field, adult, planktonic
Copepod
Taxa: Calanopia americana
Size: 0.1 - 1.0 mm
Place: Canal de São Sebastião, São Sebastião, SP, Brazil
Tags: cebimar-usp, dark-field, adult, planktonic
Sergestid shrimp
Taxa: Lucifer faxoni
Size: 1.0 - 10 mm
Place: Canal de São Sebastião, São Sebastião, SP, Brazil
Tags: cebimar-usp, dark-field, adult, planktonic
Tintinnid with hyaline lorica
Taxa: Xystonellopsis heros
Size: <0.1 mm
Place: Canal de São Sebastião, São Sebastião, SP, Brazil
Tags: unicellular, cebimar-usp, dic, planktonic
Tintinnid with hyaline lorica
Variation on lorica shape.
Taxa: Favella ehrenbergii
Size: <0.1 mm
Place: Canal de São Sebastião, São Sebastião, SP, Brazil
Tags: unicellular, cebimar-usp, sem, planktonic
Hydromedusa
Taxa: Laodicea undulata
Size: 10 - 100 mm
Place: Shiharama, Wakayama, Japan
Tags: jellyfish, dark-field, seto marine biological laboratory, planktonic, cnidarian tree of life project
Pilidium larva
Taxa: Nemertea
Size: 0.1 - 1.0 mm
Place: Canal de São Sebastião, São Sebastião, SP, Brazil
Tags: larva, cebimar-usp, dic, planktotrophic, planktonic
Dinoflagelate
Taxa: Ceratium
Size: <0.1 mm
Place: Canal de São Sebastião, São Sebastião, SP, Brazil
Tags: phytoplankton, unicellular, cebimar-usp, dic, planktonic
Larva
Taxa: Chaetopterus
Size: 0.1 - 1.0 mm
Place: Canal de São Sebastião, São Sebastião, SP, Brazil
Tags: larva, cebimar-usp, dark-field, planktotrophic, planktonic
Tubulariid hydroid
Actinula larva.
Taxa: Acharadria crocea
Size: 1.0 - 10 mm
Place: Yacht Club de Ilhabela, Ilhabela, SP, Brazil
Tags: larva, benthic, cebimar-usp, dark-field, artificial substrate
Pluteus
Taxa: Lytechinus variegatus
Size: 0.1 - 1.0 mm
Place: Canal de São Sebastião, São Sebastião, SP, Brazil
Tags: larva, cebimar-usp, dark-field, planktonic
Cubozoan
Adult medusa.
Taxa: Carybdea mora
Size: 1.0 - 10 mm
Place: Seto fishing port, Shiharama, Wakayama, Japan
Tags: jellyfish, macrophotography, seto marine biological laboratory, planktonic, cnidarian tree of life project
Starfish bipinnaria larva
Taxa: Asteroidea
Size: 0.1 - 1.0 mm
Place: Canal de São Sebastião, São Sebastião, SP, Brazil
Tags: larva, cebimar-usp, dark-field, planktotrophic, planktonic
Mysid shrimp
Taxa: Mysidopsis juniae
Size: 1.0 - 10 mm
Place: Praia do Segredo, São Sebastião, SP, Brazil
Tags: demersal, cebimar-usp, adult, planktonic, bright-field
Bryozoan larva (cyphonautes)
One type of larva typical of bryozoans, cyphonauts spend weeks in the water column until settling on a substrate such as rocks or algae, undergoing metamorphosis into the adult form and creating a new colony.
Taxa: Ectoprocta
Size: 0.1 - 1.0 mm
Place: Canal de São Sebastião, São Sebastião, SP, Brazil
Tags: larva, cebimar-usp, dic, planktotrophic, planktonic
Comb jelly or ctenophore
Cydippid larva.
Taxa: Mnemiopsis leidyi
Size: 1.0 - 10 mm
Place: Canal de São Sebastião, São Sebastião, SP, Brazil
Tags: larva, macrophotography, cebimar-usp, planktonic
Copepod
Female
Taxa: Centropages velificatus
Size: 0.1 - 1.0 mm
Place: Canal de São Sebastião, São Sebastião, SP, Brazil
Tags: cebimar-usp, dark-field, adult, planktonic
Copepod
Courtship ritual between a male and a female.
Taxa: Oncaea media
Size: 0.1 - 1.0 mm
Place: Canal de São Sebastião, São Sebastião, SP, Brazil
Tags: cebimar-usp, dic, adult, planktonic
Copepod
Taxa: Thaumatopsyllidae
Size: <0.1 mm
Place: Canal de São Sebastião, São Sebastião, SP, Brazil
Tags: cebimar-usp, dark-field, adult, planktonic
Zoea larva
Taxa: Decapoda
Size: 0.1 - 1.0 mm
Place: Canal de São Sebastião, São Sebastião, SP, Brazil
Tags: larva, cebimar-usp, dark-field, planktotrophic, planktonic
Comb jelly or ctenophore
Adult specimen.
Taxa: Mnemiopsis leidyi
Size: 10 - 100 mm
Place: Canal de São Sebastião, São Sebastião, SP, Brazil
Tags: macrophotography, cebimar-usp, adult, planktonic
Tintinnid with agglutinated lorica
Taxa: Codonellopsis ostenfeldi
Size: <0.1 mm
Place: Canal de São Sebastião, São Sebastião, SP, Brazil
Tags: unicellular, cebimar-usp, sem, planktonic
Peritrichian ciliate
Taxa: Vorticella oceanica
Size: 0.1 - 1.0 mm
Place: Canal de São Sebastião, São Sebastião, SP, Brazil
Tags: unicellular, cebimar-usp, planktonic, bright-field
Dinoflagelate
Taxa: Dinophysis
Size: <0.1 mm
Place: Canal de São Sebastião, São Sebastião, SP, Brazil
Tags: unicellular, cebimar-usp, planktonic, bright-field
Dinoflagelate
Taxa: Balechina coeruleus
Size: <0.1 mm
Place: Canal de São Sebastião, São Sebastião, SP, Brazil
Tags: unicellular, cebimar-usp, planktonic, bright-field
Actinotroch larva
Most phoronids have indirect development, with the formation of a planktotrophic larva called actinotroch. Actinotroch larvae spend weeks in the water column before settling in the habitat of the adult, which includes both consolidated and unconsolidated substrates, depending on the species.
Taxa: Phoronida
Size: 0.1 - 1.0 mm
Place: Canal de São Sebastião, São Sebastião, SP, Brazil
Tags: larva, cebimar, dic, planktotrophic, planktonic
Tornaria larva
Taxa: Hemichordata
Size: 0.1 - 1.0 mm
Place: Canal de São Sebastião, São Sebastião, SP, Brazil
Tags: larva, cebimar-usp, dic, planktotrophic, planktonic
Spionid polychaete
6-chaetiger pelagic larva.
Taxa: Pseudopolydora rosebelae
Size: 1.0 - 10 mm
Place: Praia do Sino, Ilhabela, SP, Brazil
Tags: cebimar-usp, dic, planktotrophic, planktonic
Larva de peixe
Taxa: Teleostei
Size: 0.1 - 1.0 mm
Place: Canal de São Sebastião, São Sebastião, SP, Brazil
Tags: larva, cebimar-usp, dic, planktonic
Zoanthina larva
The zoanthids have two types of larvae. The zoanthellas are cylindrical and have an ventral band of long cilia. The zoanthinas are oval or slightly elongated, with an equatorial band of cilia.
Taxa: Zoanthidea
Size: >100 mm
Place: Canal de São Sebastião, São Sebastião, SP, Brazil
Tags: larva, benthic, cebimar-usp, dark-field, rocky-shore
Brittle star larva
Taxa: Ophiuroidea
Size: 0.1 - 1.0 mm
Place: Canal de São Sebastião, São Sebastião, SP, Brazil
Tags: larva, cebimar-usp, dic, planktotrophic, planktonic
Tintinnid with agglutinated lorica
Taxa: Tintinnopsis tocantinensis
Size: <0.1 mm
Place: Canal de São Sebastião, São Sebastião, SP, Brazil
Tags: unicellular, cebimar-usp, sem, planktonic
Ciliate
Taxa: Hemicyclostina marina
Size: <0.1 mm
Place: Canal de São Sebastião, São Sebastião, SP, Brazil
Tags: unicellular, cebimar-usp, planktonic, bright-field
Sergestid shrimp
Taxa: Lucifer faxoni
Size: 1.0 - 10 mm
Place: Canal de São Sebastião, São Sebastião, SP, Brazil
Tags: cebimar-usp, dark-field, adult, planktonic
Mantis shrimp larva
Taxa: Stomatopoda
Place: Canal de São Sebastião, São Sebastião, SP, Brazil
Tags: larva, cebimar-usp, dark-field, planktotrophic, planktonic
Tintinnid with hyaline lorica
Taxa: Favella ehrenbergii
Size: <0.1 mm
Place: Canal de São Sebastião, São Sebastião, SP, Brazil
Tags: unicellular, cebimar-usp, dic, planktonic
Comb jelly or ctenophore
Taxa: Beroe ovata
Size: 10 - 100 mm
Place: Canal de São Sebastião, São Sebastião, SP, Brazil
Tags: macrophotography, cebimar-usp, adult, planktonic
Pelagosphaera larva
Named pelagosphaerae, the larvae of many species of sipunculan worms are transparent and swim freely in the water column for months before they become the adult stage which has a vermiform appearance and lives buried in sand or mud.
Taxa: Sipunculidae
Size: 0.1 - 1.0 mm
Place: Canal de São Sebastião, São Sebastião, SP, Brazil
Tags: larva, cebimar-usp, dark-field, planktotrophic, planktonic
Polychaete epitoke with egg mass
Taxa: Proceraea
Size: 0.1 - 1.0 mm
Place: Canal de São Sebastião, São Sebastião, SP, Brazil
Tags: cebimar-usp, dark-field, adult, planktonic
Dinoflagelate
Taxa: Ceratium
Size: <0.1 mm
Place: Canal de São Sebastião, São Sebastião, SP, Brazil
Tags: phytoplankton, unicellular, cebimar-usp, dic, planktonic
Mitraria larva
Taxa: Oweniidae
Size: 0.1 - 1.0 mm
Place: Canal de São Sebastião, São Sebastião, SP, Brazil
Tags: larva, cebimar-usp, dic, planktotrophic, planktonic
Larva veliger
Taxa: Gastropoda
Size: 0.1 - 1.0 mm
Place: Canal de São Sebastião, São Sebastião, SP, Brazil
Tags: larva, cebimar-usp, dark-field, planktotrophic, planktonic
Pelagosphaera larva
Named pelagosphaerae, the larvae of many species of sipunculan worms are transparent and swim freely in the water column for months before they become the adult stage which has a vermiform appearance and lives buried in sand or mud.
Taxa: Sipunculidae
Size: 0.1 - 1.0 mm
Place: Canal de São Sebastião, São Sebastião, SP, Brazil
Tags: larva, cebimar-usp, dark-field, planktotrophic, planktonic
Larva
Taxa: Chaetopterus
Size: 0.1 - 1.0 mm
Place: Canal de São Sebastião, São Sebastião, SP, Brazil
Tags: larva, cebimar-usp, dark-field, planktotrophic, planktonic
Larva
Taxa: Terebellidae
Size: 0.1 - 1.0 mm
Place: Canal de São Sebastião, São Sebastião, SP, Brazil
Tags: larva, cebimar-usp, dark-field, planktotrophic, planktonic
Hydromedusa
Adult medusa.
Taxa: Liriope tetraphylla
Size: 1.0 - 10 mm
Place: Canal de São Sebastião, São Sebastião, SP, Brazil
Tags: jellyfish, macrophotography, cebimar-usp, planktonic
Hydromedusa
Adult medusa. The jellyfish Olindas sambaquiensis is common in the southeastern coast of Brazil, especially in winter and autumn. The swimmers known them by their vivid color stinging tentacles.
Taxa: Olindias sambaquiensis
Size: >100 mm
Place: Canal de São Sebastião, São Sebastião, SP, Brazil
Tags: jellyfish, macrophotography, cebimar-usp, planktonic
Scyphozoan
Adult medusa. The juvenile stage the spider crab Libinia ferreirae can be seen inside the bell of the jellyfish Lychnorhiza lucerna.
Taxon: Libinia ferreirae, Lychnorhiza lucerna
Size: 10 - 100 mm
Place: Canal de São Sebastião, São Sebastião, SP, Brazil
Tags: symbiosis, jellyfish, macrophotography, cebimar-usp, adult, planktonic
Scyphozoan
Adult medusa
Taxa: Mastigias papua
Size: 1.0 - 10 mm
Place: Seto fishing port, Shiharama, Wakayama, Japan
Tags: jellyfish, macrophotography, seto marine biological laboratory, planktonic, cnidarian tree of life project
Hydromedusa
Taxa: Leuckartiara
Size: 10 - 100 mm
Place: Canal de São Sebastião, São Sebastião, SP, Brazil
Tags: jellyfish, macrophotography, cebimar-usp, planktonic
Symbiotic copepod associated with a planktonic invertebrate
The copepod S. angusta lives in the body cavity of the planktonic tunicate Thalia democratica, feeding on its tissues, which may cause the death of the host.
Taxon: Sapphirina angusta, Thalia democratica
Size: 0.1 - 1.0 mm
Place: Canal de São Sebastião, São Sebastião, SP, Brazil
Tags: symbiosis, cebimar-usp, dark-field, adult, parasite, planktotrophic, planktonic
Megalopa larva
Taxa: Portunidae
Size: 0.1 - 1.0 mm
Place: Canal de São Sebastião, São Sebastião, SP, Brazil
Tags: larva, cebimar-usp, dark-field, planktotrophic, planktonic
Planktonic amphipod
Taxa: Hyperiidae
Size: 0.1 - 1.0 mm
Place: Canal de São Sebastião, São Sebastião, SP, Brazil
Tags: cebimar-usp, dark-field, adult, planktonic
Comb jelly or ctenophore
Adult specimen.
Taxa: Bolinopsis vitrea
Size: 10 - 100 mm
Place: Canal de São Sebastião, São Sebastião, SP, Brazil
Tags: macrophotography, cebimar-usp, adult, planktonic
Copepod
Courtship ritual between a male and a female.
Taxa: Corycaeus giesbrechti
Size: 0.1 - 1.0 mm
Place: Canal de São Sebastião, São Sebastião, SP, Brazil
Tags: cebimar-usp, dark-field, adult, planktonic
Ostracod
Taxa: Ostracoda
Size: 0.1 - 1.0 mm
Place: Canal de São Sebastião, São Sebastião, SP, Brazil
Tags: cebimar-usp, dark-field, adult, planktonic
Crustacean larva
Taxa: Porcellanidae
Size: 0.1 - 1.0 mm
Place: Canal de São Sebastião, São Sebastião, SP, Brazil
Tags: larva, cebimar-usp, dark-field, planktotrophic, planktonic
Planctonic protozoan
Taxa: Sticholonche zanclea
Size: 0.1 - 1.0 mm
Place: Canal de São Sebastião, São Sebastião, SP, Brazil
Tags: cebimar, unicellular, dic, planktonic
Larva veliger
Taxa: Gastropoda
Size: 0.1 - 1.0 mm
Place: Canal de São Sebastião, São Sebastião, SP, Brazil
Tags: larva, cebimar-usp, dic, planktotrophic, planktonic
Plankton: microscopic giants
Although generally small in size, planktonic beings are giants in stature. Basis of marine food chains, the plankton (Greek planktos, drifting) comprises a great diversity of uni- and multicellular organisms that live dispersed in water. This community is largely less than 0.01 mm to a few centimeters, but there are notable exceptions such as jellyfish and the Portuguese man-of-war, which tentacles can reach meters in length. Many swim well, but not enough to overcome the force of water. Therefore, they roam freely, being transported by marine currents.
In addition to being small, planktonic organisms are also transparent or translucent, and easily overlooked ― examining them requires the use of microscopes and special collecting devices, as several kinds of plankton nets. However, they are very abundant and reproduce with incredible speed. One liter of seawater can contain tens of thousands of these small organisms. Many of them are primary producers, i.e., perform photosynthesis, and are called phytoplankton. The phytoplankton, which includes several groups of "microalgae" that live only in the well-lit upper layer of oceans water, produces much of the atmospheric oxygen, and serve as food for a portion of the plankton unable to get energy directly from sunlight and that depends on it for survival, the zooplankton.
Besides feeding on phytoplankton, zooplankton species can consume bacteria and particulate organic matter. And, in turn, they serve as food for larger organisms, including other species of zooplankton, fish and even whales.
Many organisms spend all their life cycle in the plankton, such as both unicellular and invertebrate species: copepods, mollusks, crustaceans, polychaetes, etc. But the plankton community is also composed by the larvae of invertebrates and some fish whose adults inhabit the seabed or the water column (see the tour Marine larvae).
The plankters live in a physically different world than ours. In their environment, viscous forces prevail over their microscopic bodies, which have "difficulty" moving. To better understand this phenomenon, imagine yourself in a pool of molasses, in which it is only possible to swim or move any part of your body in slow motion. It is in this kind of environment that planktonic organisms obtain food and reproduce for millions of years.