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...)
Whale barnacles passively filter food, using tentacle-like cirri, as the host swims through the water. The arrangement is generally considered commensal as it is done at no cost or benefit to the host. However, some whales may make use of the barnacles as protective armor or for inflicting more damage while fighting, which would make the relationship mutualistic where both parties benefit; alternatively, some species may just increase the drag that the host experiences while swimming, making the barnacles parasites. (Full article...)
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The porbeagle or porbeagle shark (Lamna nasus) is a species of mackerel shark in the familyLamnidae, distributed widely in the cold and temperate marine waters of the North Atlantic and Southern Hemisphere. In the North Pacific, its ecological equivalent is the closely related salmon shark (L. ditropis). It typically reaches 2.5 m (8.2 ft) in length and a weight of 135 kg (298 lb); North Atlantic sharks grow larger than Southern Hemisphere sharks and differ in coloration and aspects of life history. Gray above and white below, the porbeagle has a very stout midsection that tapers towards the long, pointed snout and the narrow base of the tail. It has large pectoral and first dorsal fins, tiny pelvic, second dorsal, and anal fins, and a crescent-shaped caudal fin. The most distinctive features of this species are its three-cusped teeth, the white blotch at the aft base of its first dorsal fin, and the two pairs of lateral keels on its tail.
The porbeagle is an opportunistic hunter that preys mainly on bony fishes and cephalopods throughout the water column, including the bottom. Most commonly found over food-rich banks on the outer continental shelf, it makes occasional forays both close to shore and into the open ocean to a depth of 1,360 m (4,460 ft). It also conducts long-distance seasonal migrations, generally shifting between shallower and deeper water. The porbeagle is fast and highly active, with physiological adaptations that enable it to maintain a higher body temperature than the surrounding water. It can be solitary or gregarious, and has been known to perform seemingly playful behavior. This shark is aplacental viviparous with oophagy, developing embryos being retained within the mother's uterus and subsisting on non-viable eggs. Females typically bear four pups every year. (Full article...)
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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...)
Phoronids (scientific name Phoronida, sometimes called horseshoe worms) are a small phylum of marine animals that filter-feed with a lophophore (a "crown" of tentacles), and build upright tubes of chitin to support and protect their soft bodies. They live in most of the oceans and seas, including the Arctic Ocean but excluding the Antarctic Ocean, and between the intertidal zone and about 400 meters down. Most adult phoronids are 2 cm long and about 1.5 mm wide, although the largest are 50 cm long.
The sea otter (Enhydra lutris) is a marine mammal native to the coasts of the northern and eastern North Pacific Ocean. Adult sea otters typically weigh between 14 and 45 kg (30 and 100 lb), making them the heaviest members of the weasel family, but among the smallest marine mammals. Unlike most marine mammals, the sea otter's primary form of insulation is an exceptionally thick coat of fur, the densest in the animal kingdom. Although it can walk on land, the sea otter is capable of living exclusively in the ocean.
The sea otter inhabits nearshore environments, where it dives to the sea floor to forage. It preys mostly on marine invertebrates such as sea urchins, various mollusks and crustaceans, and some species of fish. Its foraging and eating habits are noteworthy in several respects. Its use of rocks to dislodge prey and to open shells makes it one of the few mammal species to use tools. In most of its range, it is a keystone species, controlling sea urchin populations which would otherwise inflict extensive damage to kelp forestecosystems. Its diet includes prey species that are also valued by humans as food, leading to conflicts between sea otters and fisheries. (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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Scleractinian corals, illustration by Ernst Haeckel, 1904
Scleractinia, also called stony corals or hard corals, are marine animals in the phylumCnidaria that build themselves a hard skeleton. The individual animals are known as polyps and have a cylindrical body crowned by an oral disc in which a mouth is fringed with tentacles. Although some species are solitary, most are colonial. The founding polyp settles and starts to secrete calcium carbonate to protect its soft body. Solitary corals can be as much as 25 cm (10 in) across but in colonial species the polyps are usually only a few millimetres in diameter. These polyps reproduce asexually by budding, but remain attached to each other, forming a multi-polyp colony of clones with a common skeleton, which may be up to several metres in diameter or height according to species.
The shape and appearance of each coral colony depends not only on the species, but also on its location, depth, the amount of water movement and other factors. Many shallow-water corals contain symbiont unicellular organisms known as zooxanthellae within their tissues. These give their colour to the coral which thus may vary in hue depending on what species of symbiont it contains. Stony corals are closely related to sea anemones, and like them are armed with stinging cells known as cnidocytes. Corals reproduce both sexually and asexually. Most species release gametes into the sea where fertilisation takes place, and the planula larvae drift as part of the plankton, but a few species brood their eggs. Asexual reproduction is mostly by fragmentation, when part of a colony becomes detached and reattaches elsewhere. (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...)
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Black coral colony
Antipatharians, also known as black corals or thorn corals, are an order of soft deep-water corals. These corals can be recognized by their jet-black or dark brown chitin skeletons, which are surrounded by their colored polyps (part of coral that is alive). Antipatharians are a cosmopolitan order, existing in nearly every oceanic location and depth, with the sole exception of brackish waters. However, they are most frequently found on continental slopes under 50 m (164 ft) deep. A black coral reproduces both sexually and asexually throughout its lifetime. Many black corals provide housing, shelter, food, and protection for other animals.
Black corals were originally classified in the subclass Ceriantipatharia along with ceriantharians (tube-dwelling anemones), but were later reclassified under Hexacorallia. Though they have historically been used by Pacific Islanders for medical treatment and in rituals, its only modern use is making jewelry. Black corals have been declining in numbers and are expected to continue declining due to the effects of poaching, ocean acidification and climate change. (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...)
Biological oceanography is the study of how organisms affect and are affected by the physics, chemistry, and geology of the oceanographic system. Biological oceanography may also be referred to as ocean ecology, in which the root word of ecology is Oikos (oικoσ), meaning ‘house’ or ‘habitat’ in Greek. With that in mind, it is of no surprise then that the main focus of biological oceanography is on the microorganisms within the ocean; looking at how they are affected by their environment and how that affects larger marine creatures and their ecosystem. Biological oceanography is similar to marine biology, but is different because of the perspective used to study the ocean. Biological oceanography takes a bottom-up approach (in terms of the food web), while marine biology studies the ocean from a top-down perspective. Biological oceanography mainly focuses on the ecosystem of the ocean with an emphasis on plankton: their diversity (morphology, nutritional sources, motility, and metabolism); their productivity and how that plays a role in the global carbon cycle; and their distribution (predation and life cycle). (Full article...)
Image 1Phylogenetic and symbiogenetic tree of living organisms, showing a view of the origins of eukaryotes and prokaryotes (from Marine fungi)
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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 3Sea ice food web and the microbial loop. AAnP = aerobic anaerobic phototroph, DOC = dissolved organic carbon, DOM = dissolved organic matter, POC = particulate organic carbon, PR = proteorhodopsins. (from Marine food web)
Image 4Ernst 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 10Microplastics found in sediments on the seafloor (from Marine habitat)
Image 11Halfbeak as larvae are one of the organisms adapted to the unique properties of the microlayer (from Marine habitat)
Image 12In 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 13Anthropogenic stressors to marine species threatened with extinction (from Marine food web)
Image 18Conference events, such as the events hosted by the United Nations, help to bring together many stakeholders for awareness and action. (from Marine conservation)
Solar radiation can have positive (+) or negative (−) effects resulting in increases or decreases in the heterotrophic activity of bacterioplankton. (from Marine prokaryotes)
Image 26Chytrid 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 27Oceanic 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 30Jellyfish are easy to capture and digest and may be more important as food sources than was previously thought. (from Marine food web)
Image 31Scanning 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 32A 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 34Antarctic 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 35Estuaries 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 41Cryptic 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 42Lampreys are often parasitic and have a toothed, funnel-like sucking mouth (from Marine vertebrate)
Image 43Waves 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 45Tidepools on rocky shores make turbulent habitats for many forms of marine life (from Marine habitat)
Image 46The 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 47Only 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 48Cnidarians 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 50Sponges have no nervous, digestive or circulatory system (from Marine invertebrates)
Image 51This 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 52Ocean or marine biomass, in a reversal of terrestrial biomass, can increase at higher trophic levels. (from Marine food web)
Image 56Cycling 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 57Sandy shores provide shifting homes to many species (from Marine habitat)
Image 59On 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 60Food 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 64Phylogenetic 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 65Conceptual diagram of faunal community structure and food-web patterns along fluid-flux gradients within Guaymas seep and vent ecosystems. (from Marine food web)
Image 66Archaea 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 68Reconstruction 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)
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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)
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 76Elevation-area graph showing the proportion of land area at given heights and the proportion of ocean area at given depths (from Marine habitat)
Image 78The 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)
Image 81Ocean 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 85The 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 86640 μm microplastic found in the deep sea amphipod Eurythenes plasticus (from Marine habitat)
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)
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 105Biomass pyramids. Compared to terrestrial biomass pyramids, aquatic pyramids are generally inverted at the base. (from Marine food web)
Image 106Some lobe-finned fishes, like the extinct Tiktaalik, developed limb-like fins that could take them onto land (from Marine vertebrate)
Image 108An 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 109The 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 110Topological 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 111Dickinsonia may be the earliest animal. They appear in the fossil record 571 million to 541 million years ago. (from Marine invertebrates)
Image 117A 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 118Some 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 122Common-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 124Schematic 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 9Global map of large marine ecosystems. Oceanographers and biologists have identified 66 LMEs worldwide. (from Marine ecosystem)
Image 10Ecosystem 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 Humpback Whales song is produced by them forcing air through their massive nasal cavities
... all whales and dolphins have the remains of the pelvis, but it is reduced to two small bones at the rear of the animal.
... on average, a whale or dolphin will eat four to five percent of its body weight in food per day. That means that a 100 ton blue whale will eat almost five tons of krill per day, or that a 200kg bottlenose dolphin will eat 10kg of fish per day!
... whale and dolphin mothers ‘suckle’ their young underwater! Mothers have muscular mammary glands and ‘squirt’ their milk into the calf’s mouth, to ensure that the calf takes in as much of the energy rich milk as possible.
... That sharks are not known to bite humans as often as people think.
... In sand tiger sharks and several other species, the biggest, strongest pups eat the others while still inside their mother’s body.