Spawn (biology)
Spawn is the
- rays, etc.)
- Crustaceans (such as crabs, shrimps, etc.)
- )
- sea cucumbers, etc.)
- newts)
- mosquitoes)
- Coral, which are living colonies of tiny, aquatic organisms—not plants, as they are sometimes perceived to be. Corals, while appearing sedentary or botanical by nature, actually spawn by releasing clouds of sperm and egg cells into the water column, where the two mix.
All other aquatic or amphibious creatures, by a large margin, reproduce through
- whales)
- sea lions, walrus)
- )
- Mustelids (Eurasian otter and sea otters, mink, etc.)
- Water shrews
- sea turtlesand freshwater turtles)
- alligators
- sea kraits)
- Marine iguanas
- albatrosses, etc.
Spawn consists of the reproductive cells (
The
There are many variations in the way spawning occurs, depending on sexual differences in anatomy, how the sexes relate to each other, where and how the spawn is released and whether or how the spawn is subsequently guarded.
Overview
Marine animals, and particularly
Internally, the sexes of most marine animals can be determined by looking at the
Externally, many marine animals, even when spawning, show little
A species is
Semelparity is sometimes called "big bang" reproduction, since the single reproductive event of semelparous organisms is usually large and fatal to the spawners.. However, most fish and other spawning animals are iteroparous.
When the internal ovaries or egg masses of fish and certain marine animals are ripe for spawning they are called roe. Roe from certain species, such as shrimp, scallop, crab and sea urchins, are sought as human delicacies in many parts of the world. Caviar is a name for the processed, salted roe of non-fertilized sturgeon. The term soft roe or white roe denotes fish milt. Lobster roe is called coral because it turns bright red when cooked. Roe (reproductive organs) are usually eaten either raw or briefly cooked.
"The reproductive behaviour of fishes is remarkably diversified: they may be oviparous (lay eggs), ovoviviparous (retain the eggs in the body until they hatch), or viviparous (have a direct tissue connection with the developing embryos and give birth to live young). All cartilaginous fishes—the elasmobranches (e.g., sharks, rays, and skates)—employ internal fertilization and usually lay large, heavy-shelled eggs or give birth to live young. The most characteristic features of the more primitive bony fishes is the assemblage of polyandrous (many males) breeding aggregations in open water and the absence of parental care..."[7]
There are two main reproduction methods in fish. The first method is by laying eggs and the second by live-bearing (producing their young alive).
- In the first method, the female fish lays eggs either on the sea floor or on the leaves of an aquatic plant. A male fish fertilizes the eggs, and both then work together to protect the eggs/babies from danger until they can defend themselves.
- In the second method, the male fish uses its anal fin to transmit sperm into the female fish and fertilize the fish eggs. Later, the female gives live birth to her fry.
Sexual strategies
Basic strategies
Single female | Multiple females | |
---|---|---|
Single male | Monogamy | Polygyny |
Multiple males | Polyandry | Polygynandry |
Polygyny occurs when one male gets exclusive mating rights with multiple females. In polygyny, a large conspicuous male usually defends females from other males or defends a breeding site.[8] The females choose large males that are successfully defending prime breeding sites which the females find attractive. For example, sculpin males defend "caves" underneath rocks which are suitable for the incubation of embryos.
Another way males get to mate with several females is through the use of leks.
Polyandry occurs when one female gets exclusive mating rights with multiple males. This happens among fish like clownfish that change their sex. It can also happen when males do the brooding but cannot handle all the eggs the female produce, such as with some pipefish.[4]: 161
The males in some deep sea
Polygynandry occurs when multiple males mate indiscriminately with multiple females. This mutual promiscuity is the approach most commonly used by spawning animals, and is perhaps the "original fish mating system."[4]: 161 Common examples are forage fish, such as herrings, which form huge mating shoals in shallow water. The water becomes milky with sperm and the bottom is draped with millions of fertilized eggs.[4]: 161
Cuckoldry
Alternate male strategies which allow small males to engage in
Cuckoldry occurs in many fish species, including
Hermaphroditism
Usually hermaphrodites are
Less commonly hermaphrodites can be synchronous, meaning they simultaneously possess both ovaries and testicles and can function as either sex at any one time. Black hamlets "take turns releasing sperm and eggs during spawning. Because such egg trading is advantageous to both individuals, hamlets are typically monogamous for short periods of time–an unusual situation in fishes."[22] The sex of many fishes is not fixed, but can change with physical and social changes to the environment where the fish lives.[23]
Particularly among fishes, hermaphroditism can pay off in situations where one sex is more likely to survive and reproduce, perhaps because it is larger.
Unisexuality
It is rare to find true
Spawning strategies
This section is patterned after a classification of the spawning behaviours of fish by Balon (1975, 1984) into reproductive
Nonguarders
Nonguarders do not protect their eggs and offspring after spawning
Open substrate spawners
Nonguarders: Open substrate spawners[34]
- Pelagic spawners
- Benthic spawners
- Spawners on coarse bottoms
- Pelagic free embryo and larvae
- Benthic free embryo and larvae
- Spawners on plants
- Obligatory
- Nonobligatory
- Spawners on fine substrates
- Terrestrial spawners
Nonguarders: Brood hiders[34]
- Benthic spawners
- Crevice spawners
- Spawners on invertebrates
- Beach spawners
Open substrate spawners scatter their eggs in the environment. They usually spawn in shoals without complex courtship rituals, and males outnumber females.
Broadcast spawners: release their gametes (sperm and eggs) into open water for external fertilisation. There is no subsequent parental care.[35] About 75% of coral species are broadcasters, the majority of which are hermatypic, or reef-building corals.[36]
- Pelagic spawners: a type of broadcast spawners, spawn in the open sea, mostly near the surface. They are usually territoriality.[4]: 143
- Benthic spawners: deposit their spawn on or near the bottom of the sea (or lake). They are usually demersal fish such as cod and flatfish. These species typically spawn without ceremony; they do not engage in elaborate courtship rituals. Each female is usually followed by several males who fertilize the eggs as they are released. Various strategies ensure the eggs and embryos remain in place, and do not drift with the current. The eggs can adhere to other eggs or to whatever they are deposited on, or the eggs can be laid in long strings which are wrapped around plants or rocks. Some eggs take on water after they are released, so they can be dropped into cracks where they swell and wedge themselves in place.
- Egg scatterers: scatter adhesive or non-adhesive eggs to fall to the substrate, into plants, or float to the surface. These species do not look after their brood and even eat their own eggs. These are often schooling fish which spawn in groups or pairs, often laying a large number of small eggs. The fry hatch quickly.
- Egg depositors: deposit eggs on a substrate (tank glass, wood, rocks, plants). Egg depositors usually lay fewer eggs than egg-scatterers, although the eggs are larger. Egg depositors fall into two groups: those that care for their eggs, and those that do not. Among egg depositors that care for their eggs are cichlids and some catfish. Egg depositors that care for their young can be divided into two groups: cavity spawners and open spawners.
- Cavity spawners: lay eggs in a cave or cavity. These fish form pairs and have advanced brood care where the eggs are defended and cleaned. The eggs take a few days to hatch, and the fry are often guarded by the parents. Various catfish, Cyprinidae, and killifish make up the majority. Cavity spawners can be contrasted with open (shelter) spawners, which lay their eggs on an open surface.
Brood hiders
Brood hiders hide their eggs but do not give parental care after they have hidden them. Brood hiders are mostly benthic spawners that bury the fertilized eggs. For example, among salmon and trout the female digs a nest with her tail in gravel. These nests are called redds. The female then lays her eggs while the male fertilizes them, while both fish defend the redd if necessary from other members of the same species. Then the female buries the nest, and the nest site is abandoned. In North America, some minnows build nests out of piles of stones rather than dig holes. The minnow males have tubercles on their head and body which they use to help them defend the nest site.[4]: 145
- Egg buriers - can inhabit waters that dry up at some time of the year. An example are annual killifish which lay their eggs in mud. The parents mature quickly and lay their eggs before dying when the water dries up. The eggs remain in a dormant stage until rains stimulate hatching.
Guarders
Guarders: Substrate spawners[34]
- Rock tenders
- Plant tenders
- Terrestrial tenders
- Pelagic tenders
Guarders: Nest spawners[34]
- Rock and gravel nesters
- Sand nesters
- Plant-material nesters
- Gluemakers
- Nongluemakers
- Bubble nesters
- Hole nesters
- Misc-materials nesters
- Anemone nesters
Guarders protect their eggs and offspring after spawning by practicing parental care (also called brood care). Parental care is an "investment by parents in offspring that increases the offspring's chances of surviving (and hence reproducing). In fish, parental care can take a variety of forms including guarding, nest building, fanning, splashing, removal of dead eggs, retrieval of straying fry, external egg carrying, egg burying, moving eggs or young, ectodermal feeding, oral brooding, internal gestation, brood-pouch egg carrying, etc."[37]
Guarding males keep the embryos safe from predators, keep oxygen levels high by fanning water currents, and keep the area free from dead embryos and debris. They protect the embryos until they hatch, and often look after the larval stages as well. The time spent guarding can range from a few days to several months.[4]: 145
Substrate spawners
Some guarders build nests (nest spawners) and some do not (substrate spawners), though the difference between the two groups can be small.[4]: 142 Substrate spawners clean off a suitable area of surface suitable for egg laying, and look after the area, but they do not actively build a nest.
-
Baby paradise fish just hatched, gathered under the surface of a bubble nest
-
Anemone fish nest in an anemone. Here a male is protecting spawn produced by his partner.
Bearers
Bearers: External[34]
- Transfer brooders
- Auxiliary brooders
- Mouth brooders
- Gill-chamber brooders
- Pouch brooders
A female cichlid mouthbrooding fry which can be seen looking out her mouth
External videos Mouthbrooding tilapia — YouTube Mouthbrooding cichlid — YouTube
Bearers are fish that carry their embryos (and sometimes their young) around with them, either externally or internally.
External bearers
Internal bearers
Facultative internal bearers
The beginning of the evolutionary process of livebearing starts with
Bearers: Internal[34]
- Facultative internal bearers
- Obligate internal bearers
- Livebearers
Obligate internal bearers
The next step in the evolution of livebearing is obligate (by necessity) internal bearing, where the female retains all the embryos. "The only source of nutrition for these embryos, however, is the egg yolk, as in externally spawned eggs. This situation, also referred to as ovoviviparity, is characteristic of marine rock fishes and the Lake Baikal sculpins. This strategy allows these fish to have fecundities approaching those of pelagic fish with external fertilization, but it also enables them to protect the young during their most vulnerable stage of development. By contrast, sharks and rays using this strategy produce a relatively small number of embryos and retain them for a few weeks to 16 months or longer. The shorter times spans are characteristic of species that eventually deposit their embryos in the environment, surrounded by a horny capsule; whereas the longer periods are characteristic of sharks that retain the embryos until they are ready to emerge as actively swimming young."[4]: 147 [38]
Viviparous fish
However, some fish do not fit these categories. The livebearing largespring
Spawning grounds
Spawning grounds are the areas of water where aquatic animals spawn, or produce their eggs. After spawning, the spawn may or may not drift to new grounds which become their nursery grounds. Many species undertake
Forage fish often make great migrations between their spawning, feeding and nursery grounds. Schools of a particular stock usually travel in a triangle between these grounds. For example, one stock of herrings have their spawning ground in southern Norway, their feeding ground in Iceland, and their nursery ground in northern Norway. Wide triangular journeys such as these may be important because forage fish, when feeding, cannot distinguish their own offspring.[42]
Capelin are a forage fish of the smelt family found in the Atlantic and Arctic oceans. In summer, they graze on dense swarms of plankton at the edge of the ice shelf. Larger capelin also eat krill and other crustaceans. The capelin move inshore in large schools to spawn and migrate in spring and summer to feed in plankton rich areas between Iceland, Greenland, and Jan Mayen. The migration is affected by ocean currents. Around Iceland maturing capelin make large northward feeding migrations in spring and summer. The return migration takes place in September to November. The spawning migration starts north of Iceland in December or January.[43]
The diagram on the right shows the main spawning grounds and
Referred to as "the greatest
Examples
Fish
Goldfish
Carp
Carp typically spawn in the spring and summer, depending on the climate and conditions. Oxygen levels of the water, availability of food, size of each fish, age, number of times the fish has spawned before and water temperature are all factors known to effect when and how many eggs each carp will spawn at any one time.[45]
Siamese fighting fish
Prior to spawning, male Siamese fighting fish build bubble nests of varying sizes at the surface of the water. When a male becomes interested in a female, he will flare his gills, twist his body, and spread his fins. The female darkens in colour and curves her body back and forth. The act of spawning takes place in a "nuptial embrace" where the male wraps his body around the female, each embrace resulting in the release of 10–40 eggs until the female is out of eggs. The male, from his side, releases milt into the water and fertilization takes place externally. During and after spawning, the male uses his mouth to retrieve sinking eggs and deposit them in the bubble nest (during mating the female sometimes assists her partner, but more often she will simply devour all the eggs that she manages to catch). Once the female has released all of her eggs, she is chased away from the male's territory, as it is likely that she'll eat the eggs due to hunger.[46] The eggs then remain in the male's care. He keeps them in the bubble nest, making sure none fall to the bottom and repairing the nest as needed. Incubation lasts for 24–36 hours, and the newly hatched larvae remain in the nest for the next 2–3 days, until their yolk sacs are fully absorbed. Afterwards the fry leave the nest and the free-swimming stage begins.[47]
-
Siamese fighting fish build bubble nests of varying sizes.
-
A pair of Siamese fighting fish spawning under their bubble nest.
-
One-day-old Siamese fighting fish larvae in a bubble nest - their yolk sacs have not yet been absorbed
-
A 15-day-old free-swimming fry of a Siamese fighting fish
Crustaceans
External videos | |
---|---|
Lobster migration train (from The Trials of Life) |
Copepods
Copepods are tiny crustaceans which usually reproduce either by broadcast spawning or by sac spawning. Broadcasting copepods scatter their eggs into the water, but sac spawners lay their eggs into an ovigerous sac. Sac spawners spawn few but relatively large eggs that develop slowly. By contrast, broadcast spawners spawn numerous small eggs that develop rapidly.[48] However, the shorter hatch times that result from broadcasting are not short enough to compensate for the higher mortality compared to sac spawners. To produce a given number of hatched eggs, broadcasters must spawn more eggs than sac spawners.[49]
Spiny lobsters
After mating, the fertilized eggs of the
Egg-bearing female lobsters migrate inshore from deeper waters to hatch their eggs, though they do not have specific spawning grounds.[55][56] These lobster migrations can occur in close single-file formation "lobster trains".
Molluscs
Pacific oysters
Oysters are broadcast spawners, that is, eggs and sperm are released into open water where fertilisation occurs. They are
The
The larvae of the Pacific oyster are planktotrophic, and are about 70 µm at the prodissoconch 1 stage. The larvae move through the water column via the use of a larval foot to find suitable settlement locations. They can spend several weeks at this phase, which is dependent on water temperature, salinity and food supply. Over these weeks, larvae can disperse great distances by water currents before they metamorphose and settle as small spat. Similar to other oyster species, once the Pacific oyster larvae find a suitable habitat, they attach to it permanently using cement secreted from a gland in their foot. After settlement, the larvae metamorphose into juvenile spat. The growth rate is very rapid in optimum environmental conditions, and market size can be achieved in 18 to 30 months.[59]
External videos | |
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Squid spawning |
Cephalopods
Cephalopods, such as squid and octopuses, have prominent heads and a set of arms (tentacles) modified from the primitive foot of molluscs. All cephalopods are sexually dimorphic. However, they lack external sexual characteristics, so they use colour communication. A courting male approaches a likely looking mate flashing his brightest colours, often in rippling displays. If the other cephalopod is female and receptive, her skin will change colour to become pale, and mating will occur. If the other cephalopod remains brightly coloured, it is taken as a warning.[60]
All cephalopods reproduce by spawning
Some species brood their fertilized eggs: female
Echinoderms
External videos | |
---|---|
Sea urchin spawning |
Sea urchins
Sea cucumbers
Sea cucumbers are typically
Amphibious animals
Amphibians have successfully solved most of the problems associated with exposure to air. But their reproductive system was and is linked to water, and it remains very fishlike. Almost all amphibians spawn in water and lay a great number of small eggs that hatch quickly into swimming larvae. The eggs do not need any complex protection against drying, because if the environment dries, the larvae are doomed as well as the eggs. Thus selection has acted to encourage the selection of suitable sites for laying eggs, rather than suitable devices for protecting eggs. Both fishes and amphibians may migrate long distances for spawning, and favoured sites are often disputed vigorously.
Richard Cowen[71]: 117–8
Frogs and toads
Female frogs and toads usually spawn gelatinous egg masses containing thousands of eggs in water. Different species lay eggs in distinctive and identifiable ways. For example, the
While the length of the egg stage depends on the species and environmental conditions, aquatic eggs generally hatch within one week. Unlike salamanders and newts, frogs and toads never become sexually mature while still in their larval stage. The hatched eggs continue life as
Sea turtles
External videos | |
---|---|
Spawning sea turtle |
Some sea turtles migrate long distances between feeding and spawning grounds.
At around 45 to 75 days, the eggs hatch during the night and the hatchlings instinctively head directly into the water. This is the most dangerous time in a turtle's life. As they walk, predators such as gulls and crabs grab them. A significant percentage never make it to the ocean. Little is known of the initial life history of newly hatched sea turtles.[79] Juveniles spend three to five years in the open ocean before they settle as still-immature juveniles into their permanent shallow-water lifestyle.[80][81] It is speculated that they take twenty to fifty years to reach sexual maturity. Individuals live up to eighty years in the wild.[78] They are among the larger sea turtles, many more than a meter long and weighing up to 300 kilograms (660 lb).[82]
Aquatic insects
Aquatic insects also spawn. Mayflies "are famed for their short adult life. Some species have under an hour to mate and lay their eggs before they die. Their pre-adult stage, known as the subimago, may be even shorter - perhaps lasting just a few minutes before they moult into their adult form. Therefore a mayfly spends most of its life as a nymph, hidden from view under the water."[83]
Corals
Corals can be both
Corals predominantly reproduce
Planulae exhibit positive phototaxis, swimming towards light to reach surface waters where they drift and grow before descending to seek a hard surface to which they can attach and establish a new colony. They also exhibit positive sonotaxis, moving towards sounds that emanate from the reef and away from open water.[85] High failure rates afflict many stages of this process, and even though millions of gametes are released by each colony very few new colonies form. The time from spawning to settling is usually 2–3 days, but can be up to 2 months.[86] The larva grows into a polyp and eventually becomes a coral head by asexual budding and growth.
Synchronous spawning is very typical on the coral reef and often, even when multiple species are present, all corals spawn on the same night. This synchrony is essential so that male and female gametes can meet. Corals must rely on environmental cues, varying from species to species, to determine the proper time to release gametes into the water. The cues involve lunar changes, sunset time, and possibly chemical signalling.[36] Synchronous spawning may form hybrids and is perhaps involved in coral speciation.[87] In some places the spawn can be visually dramatic, clouding the usually clear water with gametes, typically at night.
Corals use two methods for sexual reproduction, which differ in whether the female gametes are released:
- Broadcasters, the majority of which mass spawn, rely heavily on environmental cues, because they release both sperm and eggs into the water. The corals use long-term cues such as day length, water temperature, and/or rate of temperature change. The short-term cue is most often the lunar cycle, with sunset cuing the release.[36] About 75% of coral species are broadcasters, the majority of which are hermatypic, or reef-building corals.[36] The positively buoyant gametes float towards the surface where fertilization produces planula larvae. The larvae swim towards the surface light to enter into currents, where they usually remain for two days, but sometimes up to three weeks, and in one known case two months,[86]after which they settle and metamorphose into polyps and form colonies.
- Brooders are most often ahermatypic (non-reef building) in areas of high current or wave action. Brooders release only sperm, which is negatively buoyant, and can harbor unfertilized eggs for weeks, lowering the need for mass synchronous spawning events, which do sometimes occur.[36] After fertilization the corals release planula larvae which are ready to settle.[88]
Fungi
Fungi are not plants, and require different conditions for optimal growth. Plants develop through photosynthesis, a process that converts atmospheric carbon dioxide into carbohydrates, especially cellulose. While sunlight provides an energy source for plants, mushrooms derive all of their energy and growth materials from their growth medium, through biochemical decomposition processes. This does not mean that light is an unnecessary requirement, since some fungi use light as a signal to induce fruiting. However, all the materials for growth must already be present in the growth medium. Instead of seeds, mushrooms reproduce sexually during underground growth, and asexually through spores. Either of these can be contaminated with airborne microorganisms, which will interfere with mushroom growth and prevent a healthy crop. Mycelium, or actively growing mushroom culture, is placed on growth substrate to seed or introduce mushrooms to grow on a substrate. This is also known as inoculation, spawning or adding spawn. Its main advantages are to reduce chances of contamination while giving mushrooms a firm beginning.[89][90]
Gallery
-
Spawning brittle star
-
Head of female krill with her brood sac
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Spawning sockeye salmon
-
Dead salmon after spawning
-
These lagoons, connected to the River Tees, provide a quiet backwater for fish to spawn and to take refuge in times of high water levels
-
In the middle of this weir is a fish ladder, which allows trout and salmon to pass the weir to go upriver to spawn.
See also
- Anadromous
- Egg case
- Federal Inventory of Amphibian Spawning Areas
- Ichthyoplankton
- Juvenile fish
- Milt
- Mouthbrooder
- Reproduction
- Salmon run
- Spawning bed
- Spawning triggers
- Stream pool
Notes
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- ^ Spawning Archived 2013-06-21 at the Wayback Machine Fishbase Glossary. Retrieved 3 February 2011.
- ^ Gametes Archived 2013-09-15 at the Wayback Machine Fishbase Glossary. Retrieved 3 February 2011.
- ^ ISBN 978-0-13-100847-2
- ISBN 0-7167-2829-X
- .
- ^ "spawning." Encyclopædia Britannica. Encyclopædia Britannica Online. Encyclopædia Britannica, 2011. Web. 03 Feb. 2011. <"Spawning | biology | Britannica". Archived from the original on 2012-11-02. Retrieved 2011-02-05.>
- ^ ISBN 0-19-850503-5.
- ^ Pair spawning Archived 2013-06-21 at the Wayback Machine Fishbase Glossary. Retrieved 3 February 2011.
- ISBN 0-7382-0528-1.
- S2CID 27001657.
- S2CID 4226567.
- ^ Streak spawning Archived 2015-02-10 at the Wayback Machine Fishbase Glossary. Retrieved 11 February 2011.
- ^ Spawning rush Archived 2015-02-10 at the Wayback Machine Fishbase Glossary. Retrieved 11 February 2011.
- ^ Gross MR (1984) "Sunfish, salmon, and the evolution of alternative reproductive strategies and tactics in fishes Archived 2019-05-24 at the Wayback Machine". Pages 55–75 in GW Potts and RJ Wottoon, eds. Fish reproduction: Strategies and tactics. Academic Press.
- .
- ^ a b Shapiro DY (1984) "Sex reversal and sociodemographics processes in coral reef fishes" Pages 103–116 in GW Potts and RK Wootoon, eds., Fish reproduction: Strategies and tactics, Academic Press.
- .
- ^ PMID 20394662.
- .
- S2CID 3002410.
- JSTOR 1310420.
- ^ Chan STH and Yeung WSB (1983) "Sex control and sex reversal in fish under natural conditions". Pages 171–222 in WS Hoar, DJ Randall and EM Donaldson, eds., Fish physiology 9B: Reproduction, behavior and fertility control. Academic Press.
- ^ S2CID 30244987.
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- ^ "Captive shark had 'virgin birth'". BBC News. 2007-05-23. Archived from the original on 17 December 2008. Retrieved 23 December 2008.
- Metro.co.uk. 2008-10-10. Archivedfrom the original on 2008-10-11. Retrieved 2008-10-10.
- S2CID 84740187.
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- ^ Walker, Brian (2010-11-11). "Scientists discover unknown lizard species at lunch buffet". CNN. Archived from the original on 2012-11-08. Retrieved 2010-11-11.
- ^ a b c d e f g Adapted from
- Balon EK (1975). "Reproductive guilds in fishes: A proposal and definition". J. Fish. Res. Board Can. 32 (6): 821–864. doi:10.1139/f75-110.
- Balon EK (1984) "Patterns in the evolution of reproductive styles in fishes". Pages 35–53 in GW Potts and RJ Wootton, eds., Fish reproduction: Strategies and tactics. London: Academic Press.
- Balon EK (1975). "Reproductive guilds in fishes: A proposal and definition". J. Fish. Res. Board Can. 32 (6): 821–864.
- ^ Broadcast spawners Archived 2015-09-25 at the Wayback Machine Fishbase Glossary. Retrieved 3 February 2011.
- ^ ISBN 978-0-642-32236-4.
- ^ Parental care Archived 2016-01-25 at the Wayback Machine Fishbase Glossary. Retrieved 3 February 2011.
- .
- ^ Marsh-Matthews E, Skierkowski P and DeMarais A (2001) "Direct Evidence for Mother-to-Embryo Transfer of Nutrients in the Livebearing Fish Gambusia geiseri" Copeia, 2001: 1(1-6).
- ISBN 1-4289-2016-1.
- ^ To Save the Salmon Archived 2011-05-18 at the Wayback Machine (1997) US Army Corps of Engineers.
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- ^ Barbaro1 A, Einarsson B, Birnir1 B, Sigurðsson S, Valdimarsson S, Pálsson ÓK, Sveinbjörnsson S and Sigurðsson P (2009) "Modelling and simulations of the migration of pelagic fish" Archived 2010-06-25 at the Wayback Machine ICES Journal of Marine Science, 66(5):826-838.
- ^ http://www.carp.me.uk Archived 2011-03-21 at the Wayback Machine Carp Spawning Information
- ^ Leong, Paul (2004). "Tips on Spawning Bettas". Archived from the original on 2009-03-02. Retrieved 2009-03-13.. Retrieved on March 13, 2009.
- ^ Rainwate FL and Miller EJ (1967) "Courtship and reproductive behavior of the Siamese fighting fish, Betta splendens Regan" Archived 2013-05-13 at the Wayback Machine Proceedings of the Oklahoma Academy of Science, Oklahoma State University.
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- .
- ^ a b Alice Cascorbi (February 10, 2004). "Seafood Watch Seafood Report. Spiny Lobsters, Vol. II. California Spiny Lobster Panulirus interruptus" (PDF). Monterey Bay Aquarium. Archived from the original (PDF) on July 6, 2010.
- ^ U.S. Army Corps of Engineers: TR EL–82–4. 10 pp. Archived(PDF) from the original on 2007-07-13.
- ISBN 978-92-5-103027-1. Archived from the originalon 2011-06-07.
- ^ a b c Martin W. Johnson (1960). "The offshore drift of larvae of the California spiny lobster Panulirus interruptus" (PDF). California Co-operative Oceanic Fisheries Investigations. 7: 147–161. Archived from the original (PDF) on 2011-07-20.
- JSTOR 20105816.)
{{cite journal}}
: CS1 maint: multiple names: authors list (link - ^ American Lobster (Homarus americanus) Archived 2011-01-04 at the Wayback Machine NMFS and NOAA. Updated 5 October 2010. Retrieved 3 February 2011.
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- ^ Quayle, D.B (1969). Pacific oyster culture in British Columbia, p. 23. First Edition. Ottawa: The Queen’s Printer.
- .
- ^ Pacific Oyster factsheet Archived 2012-05-13 at the Wayback Machine, Food and Agriculture Organization of the United Nations (FAO)
- ISBN 978-0-86977-115-0.)
{{cite book}}
: CS1 maint: multiple names: authors list (link - ^ Cephalopods. Archived 2007-10-20 at the Wayback Machine The Living World of Molluscs. Robert Nordsieck.
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{{cite journal}}
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Further reading
- Cole, Kathleen S (2010) Reproduction and Sexuality in Marine Fishes: Patterns and Processes University of California Press. ISBN 978-0-520-26433-5.
External links
- Reproduction FAO, Rome.