Marine invertebrates exhibit a wide range of modifications to survive in poorly oxygenated waters, including breathing tubes as in mollusc siphons. Fish have gills instead of lungs, although some species of fish, such as the lungfish, have both. Marine mammals (e.g. dolphins, whales, otters, and seals) need to surface periodically to breathe air. (Full article...)
Sea urchins or urchins (/ˈɜːrtʃɪnz/) are typically spiny, globular animals, echinoderms in the class Echinoidea. About 950 species live on the seabed, inhabiting all oceans and depth zones from the intertidal to 5,000 metres (16,000 ft; 2,700 fathoms). Their tests (hard shells) are round and spiny, typically from 3 to 10 cm (1 to 4 in) across. Sea urchins move slowly, crawling with their tube feet, and sometimes pushing themselves with their spines. They feed primarily on algae but also eat slow-moving or sessile animals. Their predators include sea otters, starfish, wolf eels, and triggerfish.
Like all echinoderms, adult sea urchins have fivefold symmetry with their pluteus larvae featuring bilateral (mirror) symmetry; The latter indicates that they belong to the Bilateria, along with chordates, arthropods, annelids and molluscs. Sea urchins are found in every ocean and in every climate, from the tropics to the polar regions, and inhabit marine benthic (sea bed) habitats, from rocky shores to hadal zone depths. The fossil record of the Echinoids dates from the Ordovician period, some 450 million years ago. The closest echinoderm relatives of the sea urchin are the sea cucumbers (Holothuroidea), which like them are deuterostomes, a clade that includes the chordates. (Sand dollars are a separate order in the sea urchin class Echinoidea.) (Full article...)
The Sirenia (/saɪˈriːni.ə/), commonly referred to as sea cows or sirenians, are an order of fully aquatic, herbivorousmammals that inhabit swamps, rivers, estuaries, marine wetlands, and coastal marine waters. The extant Sirenia comprise two distinct families: Dugongidae (the dugong and the now extinct Steller's sea cow) and Trichechidae (manatees, namely the Amazonian manatee, West Indian manatee, and West African manatee) with a total of four species. The Protosirenidae (Eocene sirenians) and Prorastomidae (terrestrial sirenians) families are extinct. Sirenians are classified in the cladePaenungulata, alongside the elephants and the hyraxes, and evolved in the Eocene 50 million years ago (mya). The Dugongidae diverged from the Trichechidae in the late Eocene or early Oligocene (30–35 mya).
Sirenians grow to between 2.5 and 4 metres (8.2 and 13.1 feet) in length and 1,500 kilograms (3,300 pounds) in weight. The recently extinct Steller's sea cow was the largest known sirenian to have lived, reaching lengths of 10 metres (33 feet) and weights of 5 to 10 tonnes (5.5 to 11.0 short tons). (Full article...)
Albatrosses are highly efficient in the air, using dynamic soaring and slope soaring to cover great distances with little exertion. They feed on squid, fish, and krill by either scavenging, surface seizing, or diving. Albatrosses are colonial, nesting for the most part on remote oceanic islands, often with several species nesting together. Pair bonds between males and females form over several years, with the use of "ritualised dances", and last for the life of the pair. A breeding season can take over a year from laying to fledging, with a single egg laid in each breeding attempt. A Laysan albatross, named Wisdom, on Midway Island is the oldest-known wild bird in the world; she was first banded in 1956 by Chandler Robbins. (Full article...)
The sea mink (Neogale macrodon) is a recently extinct species of mink that lived on the eastern coast of North America around the Gulf of Maine on the New England seaboard. It was most closely related to the American mink (Neogale vison), with continuing debate about whether or not the sea mink should be considered a subspecies of the American mink (as Neogale vison macrodon) or a species of its own. The main justification for a separate species designation is the size difference between the two minks, but other distinctions have been made, such as its redder fur. The only known remains are bone fragments unearthed in Native American shell middens. Its actual size is speculative, based largely on tooth remains.
The sea mink was first described in 1903, after its extinction; information regarding its external appearance and habits stem from speculation and from accounts made by fur traders and Native Americans. It may have exhibited behavior similar to the American mink, in that it probably maintained home ranges, was polygynandrous, and had a similar diet, though more seaward-oriented. It was probably found on the New England coast and the Maritime Provinces, though its range may have stretched further south during the last glacial period. Conversely, its range may have been restricted solely to the New England coast, specifically the Gulf of Maine, or just to the nearby islands. The largest of the minks, the sea mink was more desirable to fur traders and became extinct in the late 19th or early 20th century. (Full article...)
Image 5
Sei whale mother and calf
The sei whale (/seɪ/SAY, Norwegian:[sæɪ]; Balaenoptera borealis) is a baleen whale. It is one of ten rorqual species, and the third-largest member after the blue and fin whales. They can grow up to 19.5 m (64 ft) in length and weigh as much as 28 t (28 long tons; 31 short tons). Two subspecies are recognized: B. b. borealis and B. b. schlegelii. The whale's ventral surface has sporadic markings ranging from light grey to white, and its body is usually dark steel grey in colour. It is among the fastest of all cetaceans, and can reach speeds of up to 50 km/h (31 mph) over short distances.
It inhabits most oceans and adjoining seas, and prefers deep offshore waters. It avoids polar and tropical waters and semi-enclosed bodies of water. The sei whale migrates annually from cool, subpolar waters in summer to temperate, subtropical waters in winter with a lifespan of 70 years. It is a filter feeder, with its diet consisting primarily of copepods, krill, and other zooplankton. It is typically solitary or can be found in groups numbering half a dozen. During the breeding period, a mating pair will remain together. Sei whale vocalizations usually lasts half a second, and occurs at 240–625 hertz. (Full article...)
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Crinoid on the reef of Batu Moncho Island, Indonesia
Crinoids are marine invertebrates that make up the classCrinoidea. Crinoids that are attached to the sea bottom by a stalk in their juvenile form are commonly called sea lilies, while the unstalked forms, called feather stars or comatulids, are members of the largest crinoid order, Comatulida. Crinoids are echinoderms in the phylumEchinodermata, which also includes the starfish, brittle stars, sea urchins and sea cucumbers. They live in both shallow water and in depths as great as 9,000 meters (30,000 ft).
Adult crinoids are characterised by having the mouth located on the upper surface. This is surrounded by feeding arms, and is linked to a U-shaped gut, with the anus being located on the oral disc near the mouth. Although the basic echinoderm pattern of fivefold symmetry can be recognised, in most crinoids the five arms are subdivided into ten or more. These have feathery pinnules and are spread wide to gather planktonic particles from the water. At some stage in their lives, most crinoids have a short stem used to attach themselves to the substrate, but many live attached only as juveniles and become free-swimming as adults. (Full article...)
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Monk seals are earless seals of the tribeMonachini. They are the only earless seals found in tropical climates. The two genera of monk seals, Monachus and Neomonachus, comprise three species: the Mediterranean monk seal, Monachus monachus; the Hawaiian monk seal, Neomonachus schauinslandi; and the Caribbean monk seal, Neomonachus tropicalis, which became extinct in the 20th century. The two surviving species are now rare and in imminent danger of extinction. All three monk seal species were classified in genus Monachus until 2014, when the Caribbean and Hawaiian species were placed into a new genus, Neomonachus.
Monk seals have a slender body and are agile. They have a broad, flat snout with nostrils on the top. Monk seals are polygynous, and group together in harems. They feed mainly on bony fish and cephalopods, but they are opportunistic. The skin is covered in small hairs, which are generally black in males and brown or dark gray in females. Monk seals are found in the Hawaiian archipelago, certain areas in the east Atlantic and Mediterranean Sea (such as Cabo Blanco and Gyaros island), and formerly in the tropical areas of the west Atlantic Ocean. (Full article...)
Image 8
Main entrance in 2016, featuring the remodeled façade and fiberglass smokestacks of the Hovden Cannery
Early proposals to build a public aquarium in Monterey County were not successful until a group of four marine biologists affiliated with Stanford University revisited the concept in the late 1970s. Monterey Bay Aquarium was built at the site of a defunct sardine cannery and has been recognized for its architectural achievements by the American Institute of Architects. Along with its architecture, the aquarium has won numerous awards for its exhibition of marine life, ocean conservation efforts, and educational programs. (Full article...)
Image 9
The orca (Orcinus orca), or killer whale, is a toothed whale that is the largest member of the oceanic dolphin family. It is the only extant species in the genus Orcinus. Orcas are recognizable by their black-and-white patterned body. A cosmopolitan species, they are found in diverse marine environments, from Arctic to Antarctic regions to tropical seas.
Orcas are apex predators with a diverse diet. Individual populations often specialize in particular types of prey. This includes a variety of fish, sharks, rays, and marine mammals such as seals and other dolphins and whales. They are highly social; some populations are composed of highly stable matrilineal family groups (pods). Their sophisticated hunting techniques and vocal behaviors, often specific to a particular group and passed along from generation to generation, are considered to be manifestations of animal culture. (Full article...)
Image 3Estuaries occur when rivers flow into a coastal bay or inlet. They are nutrient rich and have a transition zone which moves from freshwater to saltwater. (from Marine habitat)
Image 7An in situ perspective of a deep pelagic food web derived from ROV-based observations of feeding, as represented by 20 broad taxonomic groupings. The linkages between predator to prey are coloured according to predator group origin, and loops indicate within-group feeding. The thickness of the lines or edges connecting food web components is scaled to the log of the number of unique ROV feeding observations across the years 1991–2016 between the two groups of animals. The different groups have eight colour-coded types according to main animal types as indicated by the legend and defined here: red, cephalopods; orange, crustaceans; light green, fish; dark green, medusa; purple, siphonophores; blue, ctenophores and grey, all other animals. In this plot, the vertical axis does not correspond to trophic level, because this metric is not readily estimated for all members. (from Marine food web)
Image 8Oceanic pelagic food web showing energy flow from micronekton to top predators. Line thickness is scaled to the proportion in the diet. (from Marine food web)
Image 12Food web structure in the euphotic zone. The linear food chain large phytoplankton-herbivore-predator (on the left with red arrow connections) has fewer levels than one with small phytoplankton at the base. The microbial loop refers to the flow from the dissolved organic carbon (DOC) via heterotrophic bacteria (Het. Bac.) and microzooplankton to predatory zooplankton (on the right with black solid arrows). Viruses play a major role in the mortality of phytoplankton and heterotrophic bacteria, and recycle organic carbon back to the DOC pool. Other sources of dissolved organic carbon (also dashed black arrows) includes exudation, sloppy feeding, etc. Particulate detritus pools and fluxes are not shown for simplicity. (from Marine food web)
Image 13Elevation-area graph showing the proportion of land area at given heights and the proportion of ocean area at given depths (from Marine habitat)
Image 14
Different bacteria shapes (cocci, rods and spirochetes) and their sizes compared with the width of a human hair. A few bacteria are comma-shaped (vibrio). Archaea have similar shapes, though the archaeon Haloquadratum is flat and square.
The unit μm is a measurement of length, the micrometer, equal to 1/1,000 of a millimeter
Image 15Ocean surface chlorophyll concentrations in October 2019. The concentration of chlorophyll can be used as a proxy to indicate how many phytoplankton are present. Thus on this global map green indicates where a lot of phytoplankton are present, while blue indicates where few phytoplankton are present. – NASA Earth Observatory 2019. (from Marine food web)
Image 16Cnidarians are the simplest animals with cells organised into tissues. Yet the starlet sea anemone contains the same genes as those that form the vertebrate head. (from Marine invertebrates)
Image 19Conceptual diagram of faunal community structure and food-web patterns along fluid-flux gradients within Guaymas seep and vent ecosystems. (from Marine food web)
Image 31Archaea were initially viewed as extremophiles living in harsh environments, such as the yellow archaea pictured here in a hot spring, but they have since been found in a much broader range of habitats. (from Marine prokaryotes)
Image 32Phylogenetic and symbiogenetic tree of living organisms, showing a view of the origins of eukaryotes and prokaryotes (from Marine fungi)
Image 33Whales were close to extinction until legislation was put in place. (from Marine conservation)
Image 38Topological positions versus mobility: (A) bottom-up groups (sessile and drifters), (B) groups at the top of the food web. Phyto, phytoplankton; MacroAlga, macroalgae; Proto, pelagic protozoa; Crus, Crustacea; PelBact, pelagic bacteria; Echino, Echinoderms; Amph, Amphipods; HerbFish, herbivorous fish; Zoopl, zooplankton; SuspFeed, suspension feeders; Polych, polychaetes; Mugil, Mugilidae; Gastropod, gastropods; Blenny, omnivorous blennies; Decapod, decapods; Dpunt, Diplodus puntazzo; Macropl, macroplankton; PlFish, planktivorous fish; Cephalopod, cephalopods; Mcarni, macrocarnivorous fish; Pisc, piscivorous fish; Bird, seabirds; InvFeed1 through InvFeed4, benthic invertebrate feeders. (from Marine food web)
Image 39Reconstruction of an ammonite, a highly successful early cephalopod that first appeared in the Devonian (about 400 mya). They became extinct during the same extinction event that killed the land dinosaurs (about 66 mya). (from Marine invertebrates)
Image 40Waves and currents shape the intertidal shoreline, eroding the softer rocks and transporting and grading loose particles into shingles, sand or mud (from Marine habitat)
Image 47Common-enemy graph of Antarctic food web. Potter Cove 2018. Nodes represent basal species and links indirect interactions (shared predators). Node and link widths are proportional to number of shared predators. Node colors represent functional groups. (from Marine food web)
Image 49This algae bloom occupies sunlit epipelagic waters off the southern coast of England. The algae are maybe feeding on nutrients from land runoff or upwellings at the edge of the continental shelf. (from Marine habitat)
Image 50In the open ocean, sunlit surface epipelagic waters get enough light for photosynthesis, but there are often not enough nutrients. As a result, large areas contain little life apart from migrating animals. (from Marine habitat)
Image 51Cryptic interactions in the marine food web. Red: mixotrophy; green: ontogenetic and species differences; purple: microbial cross‐feeding; orange: auxotrophy; blue: cellular carbon partitioning. (from Marine food web)
Image 52Biomass pyramids. Compared to terrestrial biomass pyramids, aquatic pyramids are generally inverted at the base. (from Marine food web)
Image 53
Diagram of a mycoloop (fungus loop)
Parasitic chytrids can transfer material from large inedible phytoplankton to zooplankton. Chytrids zoospores are excellent food for zooplankton in terms of size (2–5 μm in diameter), shape, nutritional quality (rich in polyunsaturated fatty acids and cholesterols). Large colonies of host phytoplankton may also be fragmented by chytrid infections and become edible to zooplankton. (from Marine fungi)
Mycoloop links between phytoplankton and zooplankton
Chytrid‐mediated trophic links between phytoplankton and zooplankton (mycoloop). While small phytoplankton species can be grazed upon by zooplankton, large phytoplankton species constitute poorly edible or even inedible prey. Chytrid infections on large phytoplankton can induce changes in palatability, as a result of host aggregation (reduced edibility) or mechanistic fragmentation of cells or filaments (increased palatability). First, chytrid parasites extract and repack nutrients and energy from their hosts in form of readily edible zoospores. Second, infected and fragmented hosts including attached sporangia can also be ingested by grazers (i.e. concomitant predation). (from Marine fungi)
Image 56Scanning electron micrograph of a strain of Roseobacter, a widespread and important genus of marine bacteria. For scale, the membrane pore size is 0.2 μm in diameter. (from Marine prokaryotes)
Image 57Some representative ocean animal life (not drawn to scale) within their approximate depth-defined ecological habitats. Marine microorganisms exist on the surfaces and within the tissues and organs of the diverse life inhabiting the ocean, across all ocean habitats. (from Marine habitat)
Image 59The pelagic food web, showing the central involvement of marine microorganisms in how the ocean imports nutrients from and then exports them back to the atmosphere and ocean floor (from Marine food web)
Image 73Coral reefs provide marine habitats for tube sponges, which in turn become marine habitats for fishes (from Marine habitat)
Image 74Schematic representation of the changes in abundance between trophic groups in a temperate rocky reef ecosystem. (a) Interactions at equilibrium. (b) Trophic cascade following disturbance. In this case, the otter is the dominant predator and the macroalgae are kelp. Arrows with positive (green, +) signs indicate positive effects on abundance while those with negative (red, -) indicate negative effects on abundance. The size of the bubbles represents the change in population abundance and associated altered interaction strength following disturbance. (from Marine food web)
Image 76Ernst Haeckel's 96th plate, showing some marine invertebrates. Marine invertebrates have a large variety of body plans, which are currently categorised into over 30 phyla. (from Marine invertebrates)
Image 78Tidepools on rocky shores make turbulent habitats for many forms of marine life (from Marine habitat)
Image 79Chytrid parasites of marine diatoms. (A) Chytrid sporangia on Pleurosigma sp. The white arrow indicates the operculate discharge pore. (B) Rhizoids (white arrow) extending into diatom host. (C) Chlorophyll aggregates localized to infection sites (white arrows). (D and E) Single hosts bearing multiple zoosporangia at different stages of development. The white arrow in panel E highlights branching rhizoids. (F) Endobiotic chytrid-like sporangia within diatom frustule. Bars = 10 μm. (from Marine fungi)
Image 83Cycling of marine phytoplankton. Phytoplankton live in the photic zone of the ocean, where photosynthesis is possible. During photosynthesis, they assimilate carbon dioxide and release oxygen. If solar radiation is too high, phytoplankton may fall victim to photodegradation. For growth, phytoplankton cells depend on nutrients, which enter the ocean by rivers, continental weathering, and glacial ice meltwater on the poles. Phytoplankton release dissolved organic carbon (DOC) into the ocean. Since phytoplankton are the basis of marine food webs, they serve as prey for zooplankton, fish larvae and other heterotrophic organisms. They can also be degraded by bacteria or by viral lysis. Although some phytoplankton cells, such as dinoflagellates, are able to migrate vertically, they are still incapable of actively moving against currents, so they slowly sink and ultimately fertilize the seafloor with dead cells and detritus. (from Marine food web)
Image 84The Ocean Cleanup is one of many organizations working toward marine conservation such at this interceptor vessel that prevents plastic from entering the ocean. (from Marine conservation)
Estimates of microbial species counts in the three domains of life
Bacteria are the oldest and most biodiverse group, followed by Archaea and Fungi (the most recent groups). In 1998, before awareness of the extent of microbial life had gotten underway, Robert M. May estimated there were 3 million species of living organisms on the planet. But in 2016, Locey and Lennon estimated the number of microorganism species could be as high as 1 trillion. (from Marine prokaryotes)
Image 88
The global continental shelf, highlighted in light green, defines the extent of marine coastal habitats, and occupies 5% of the total world area
Image 94A 2016 metagenomic representation of the tree of life using ribosomal protein sequences. The tree includes 92 named bacterial phyla, 26 archaeal phyla and five eukaryotic supergroups. Major lineages are assigned arbitrary colours and named in italics with well-characterized lineage names. Lineages lacking an isolated representative are highlighted with non-italicized names and red dots. (from Marine prokaryotes)
Image 95
Model of the energy generating mechanism in marine bacteria
(1) When sunlight strikes a rhodopsin molecule (2) it changes its configuration so a proton is expelled from the cell (3) the chemical potential causes the proton to flow back to the cell (4) thus generating energy (5) in the form of adenosine triphosphate. (from Marine prokaryotes)
Image 96Phylogenetic tree representing bacterial OTUs from clone libraries and next-generation sequencing. OTUs from next-generation sequencing are displayed if the OTU contained more than two sequences in the unrarefied OTU table (3626 OTUs). (from Marine prokaryotes)
Image 97A protected sea turtle area that warns of fines and imprisonment on a beach in Miami, Florida. (from Marine conservation)
Image 98The deep sea amphipodEurythenes plasticus, named after microplastics found in its body, demonstrating plastic pollution affects marine habitats even 6000m below sea level. (from Marine habitat)
Image 99640 μm microplastic found in the deep sea amphipod Eurythenes plasticus (from Marine habitat)
Image 103The distribution of anthropogenic stressors faced by marine species threatened with extinction in various marine regions of the world. Numbers in the pie charts indicate the percentage contribution of an anthropogenic stressors' impact in a specific marine region. (from Marine food web)
Image 104A microbial mat encrusted with iron oxide on the flank of a seamount can harbour microbial communities dominated by the iron-oxidizing Zetaproteobacteria (from Marine prokaryotes)
Image 113On average there are more than one million microbial cells in every drop of seawater, and their collective metabolisms not only recycle nutrients that can then be used by larger organisms but also catalyze key chemical transformations that maintain Earth's habitability. (from Marine food web)
Image 114Ocean Conservation Namibia rescuing a seal that was entangled in discarded fishing nets. (from Marine conservation)
Image 117Dickinsonia may be the earliest animal. They appear in the fossil record 571 million to 541 million years ago. (from Marine invertebrates)
Image 118
Bacterioplankton and the pelagic marine food web
Solar radiation can have positive (+) or negative (−) effects resulting in increases or decreases in the heterotrophic activity of bacterioplankton. (from Marine prokaryotes)
Image 119Antarctic marine food web. Potter Cove 2018. Vertical position indicates trophic level and node widths are proportional to total degree (in and out). Node colors represent functional groups. (from Marine food web)
Image 120Conference events, such as the events hosted by the United Nations, help to bring together many stakeholders for awareness and action. (from Marine conservation)
Image 125Only 29 percent of the world surface is land. The rest is ocean, home to the marine habitats. The oceans are nearly four kilometres deep on average and are fringed with coastlines that run for nearly 380,000 kilometres.
Image 7Ecosystem services delivered by epibenthicbivalve reefs. Reefs provide coastal protection through erosion control and shoreline stabilization, and modify the physical landscape by ecosystem engineering, thereby providing habitat for species by facilitative interactions with other habitats such as tidal flat benthic communities, seagrasses and marshes. (from Marine ecosystem)
... The teeth of carnivorous sharks are not attached to the jaw, but embedded in their flesh. In many species, teeth are constantly replaced throughout the shark's life.
... there are probably types of cetaceans that are as yet unknown. For example, the Longman's beaked whale is only known from skulls washed ashore in Somalia and Australia. It has never been seen alive!
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![Image 17Pennate diatom from an Arctic meltpond, infected with two chytrid-like [zoo-]sporangium fungal pathogens (in false-colour red). Scale bar = 10 μm. (from Marine food web)](/wiki/File:Pennate_diatom_infected_with_two_chytrid-like_fungal_pathogens.png)
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