Ikan zebra

Ikan zebra
Danio rerio
Status konservasi
Risiko rendah
IUCN	166487
Taksonomi
Kerajaan	Animalia
Filum	Chordata
Kelas	Actinopteri
Ordo	Cypriniformes
Famili	Danionidae
Genus	Danio
Spesies	Danio rerio (Hamilton, 1822, 1822)
Tata nama
Sinonim takson	Barilius rerio Brachydanio rerio Cyprinus chapalio Cyprinus rerio Danio frankei Danio lineatus Nuria rerio Perilamopus striatus
Protonim	Cyprinus rerio
Distribusi
Endemik	Asia Selatan

Ikan zebra (Danio rerio) adalah salah satu spesies ikan bermarga Danio dari keluarga siprinide.^[1] Penggunaan nama umum "ikan zebra" pada Danio rerio didasari oleh adanya garis-garis pigmen horizontal pada tubuh ikan zebra yang menyerupai garis-garis pada tubuh zebra.^[2] Ukuran tubuh ikan zebra sekitar 3–5 sentimeter dengan kulit belang berwarna biru kehitaman dan jingga kekuningan.^[3] Ikan zebra hidup di perairan yang tenang dengan permukaan tanah berpasir, berlanau, atau berkerikil di area persawahan, lahan basah, dan akuarium.^[4] Habitat asli ikan zebra adalah di negara-negara yang termasuk dalam kawasan Asia Selatan.^[5]

Siklus hidup ikan zebra dimulai dari tahap embrio, larva, ikan muda, hingga ke tahap ikan dewasa.^[6] Ikan zebra merupakan salah satu jenis ikan omnivora.^[7] Makanan ikan zebra berupa organisme hidup yang berukuran lebih kecil dari ukuran tubuhnya.^[8] Pemangsa utama bagi ikan zebra dewasa adalah ikan kepala ular, ikan gabus, dan ikan jarum air tawar.^[9] Parasit yang paling sering ditemui pada tubuh ikan zebra adalah Pseudoloma neurophilia.^[10]

Tubuh ikan zebra terdiri dari mata, mulut, otak, organ-organ pencernaan, hidung, otot, darah, tulang, dan gigi.^[11] Selain itu, ikan zebra juga memiliki lima sirip.^[12] Ikan zebra memiliki indera penglihatan yang baik serta memiliki telinga dan gurat sisi sebagai organ penyensor gerakan. Penciuman ikan zebra berfungsi sebagai sensor tanda akan adanya bahaya dan sebagai isyarat kekerabatan.^[13]

Di alam liar, ikan zebra bereproduksi setiap musim hujan, sedangkan di laboratorium, reproduksi berlangsung sepanjang tahun.^[14] Ikan zebra suka membentuk kawanan dan kelompok-kelompok yang mempunyai penampilan dan tingkah laku yang serupa.^[15] Dalam suatu kawanan ikan zebra selalu terdapat ikan pejantan yang dominan.^[15] Kehadiran pemangsa juga menimbulkan reaksi ketakutan pada ikan zebra.^[16]

Variasi genetik lebih banyak ditemukan pada ikan zebra yang berada di alam liar. Di laboratorium penelitian, variasi genetik ikan zebra sangat rendah.^[17] Ikan zebra memiliki hubungan kekerabatan dengan kelompok spesies Danio aesculapii, Danio kyathit, dan Danio nigrofsciatus, serta dengan subkelompok spesies Danio albolineatus, Danio jaintianensis, Danio quagga, dan Danio tinwini.^[18]

Saat ini, lebih dari 10.000 mutan dan beberapa jalur transgenik ikan zebra telah dihasilkan untuk mempelajari penyakit manusia.^[19] Ikan zebra memiliki beberapa karakteristik khusus yang membuat para peneliti memanfaatkannya sebagai organisme model serba guna pada berbagai bidang penelitian.^[20] Selain itu, ikan zebra cukup populer sebagai ikan hias.

1. ^ Reed, Barney & Maggy Jennings (2011), hlm. 10."Danio rerio (formerly Brachydanio rerio) is one of approximately 45 Danio species worldwide They are part of the Cyprinidae family that includes carp and minnows."
2. ^ "Zebrafish | Understanding Animal Research". Understanding Animal Research (dalam bahasa Inggris). Diarsipkan dari versi asli tanggal 2020-04-28. Diakses tanggal 05 April 2020.  Periksa nilai tanggal di: |access-date= (bantuan)
3. ^ EZRC, KIT, & Heidelberg University (2017), hlm. 33."Adult zebrafish are about 3-5 cm in length and show a characteristic pattern of blueblack horizontal stripes that run along the body and the anal and tail fins. These black stripes are formed by melanin-containing melanophore cells. The stripes are separated from each other by xanthophores, which contain pteridin and carotenoid pigments that confer an orange-yellowish colour. A third type of pigment cells, the iridophores, contains guanine-rich platelets that provide an iridescent appearance. Zebrafish exhibit sexual dimorphism, with the female characterized by a larger belly and the male by its comparative slimness and a more yellowish hue. As a ray-finned fish, zebrafish possess the basic body plan of this vertebrate group, which is distinguished by some characteristic features such as fins supported by bony rays emerging from the base of the fin, gills on both sides of the body in a cavity covered by an operculum, and a swim bladder regulating buoyancy. (...).
4. ^ EZRC, KIT, & Heidelberg University (2017), hlm. 36."Zebrafish are found all across India in a variety of habitats. Common typical characteristics of their habitats are low water flow, ground covered with sand, silt or pebbles, and overhanging vegetation. Such habitats are frequently found in secondary or tertiary channels connected with the main channel of a river, or adjacent to wetlands and paddy fields. (...). In research facilities, zebrafish are generally kept in aquaria devoid of additional structures, in order to facilitate monitoring and cleaning. Experiments involving additional tank structures attempting to mimic more “natural” environments have yielded mixed results regarding welfare benefits. for food, including other Cyprinids like Puntius barbs, other Danio species and especially Esomus danricus, which has a similar size and gape and which occupies similar positions in the water column"
5. ^ U.S. Fish & Wildlife Service (2018), hlm. 1."From Froese and Pauly: “Asia: Pakistan, India, Bangladesh, Nepal and Myanmar. Reported from Bhutan. ”From Nico et al: “Tropical Asia. Pakistan, India, Bangladesh, and Nepal. Also reported from Myanmar and Bhutan.”
6. ^ Department of Research (2018), hlm. 3."The zebrafish life cycle is defined as follow: o Embryos : 0-72 hours post-fertilization o Early larvae: 72 hours to 13 days post-fertilization o Mid larvae : 14 days to 29 days post-fertilization o Juveniles : 30 days to 3 or 4 months o Adults : When sexually mature"
7. ^ Simonetti, Rajla Bressan; Marques, Lis Santos; Jr, Danilo Pedro Streit; Oberst, Eneder Rosana (2015-07-27). "ZEBRAFISH (Danio rerio): THE FUTURE OF ANIMAL MODEL IN BIOMEDICAL RESEARCH". Journal of FisheriesSciences.com (dalam bahasa Inggris). 9 (3). ISSN 1307-234X. 
8. ^ Kesalahan pengutipan: Tag <ref> tidak sah; tidak ditemukan teks untuk ref bernama :3
9. ^ Spence et al. (2008), hlm. 16."The most common predatory tax a captured with zebrafish were snakeheads, Channa spp., and the freshwater garfish, Xenentodon cancila (...). Mastacembelids, which also co-occur with zebrafish, are oophagous and may be predators of zebrafish eggs and embryos, while odonate larvae may be predators of larval and juvenile zebrafish (...). Adult zebrafish are also predators of zebrafish eggs and larvae. Avian predators such as the Indian pond heron, Ardeola grayii (Sykes) and the common kingfisher, Alcedo atthis L., are also ubiquitous in the floodplains of the Indian subcontinent and may feed on D. rerio."
10. ^ Sanders et al. (2012), hlm. 107."Pseudoloma neurophilia is the most commonly observed microsporidian parasite of zebrafish; (...). It generally causes chronic infections in zebrafish, with clinical signs ranging from emaciation and obvious spinal deformities (lordosis, scoliosis) to subclinical infections exhibiting no outward signs of disease (...). (...), experiments using zebrafish with these infections may be subject to nonexperimental variation, potentially confounding results, (...). Furthermore, infected fish without overt clinical disease have been shown to have reduced fecundity and size."
11. ^ Burke, Elizabeth (2016-08-08). "Why Use Zebrafish to Study Human Diseases?". NIH Intramural Research Program (dalam bahasa Inggris). Diakses tanggal 20 Maret 2020. 
12. ^ Kesalahan pengutipan: Tag <ref> tidak sah; tidak ditemukan teks untuk ref bernama :4
13. ^ EZRC, KIT, & Heidelberg University (2017), hlm. 33-34."Zebrafish have also served to study more fish-specific aspects of physiology related to its aquatic habitat, such as osmoregulation by ionocytes in the gills (...). Mechanosensory systems of the zebrafish are the lateral line organ and the ear. The lateral line is composed of a series of mechanosensory receptors (hair cells) on the head and along the body axis, which detect e.g. vibrations in the water (...). The ear is composed of an inner ear only. The hair cell containing macula organs of this ear serve both as balance organs, as they do in mammals, and additionally for hearing. As the zebrafish forms part of the Otophysi group of fish, its inner ear is linked to the swim bladder by small bones (the Weberian ossicles). This enhances hearing and makes the zebrafish one of the “hearing specialists” among the fishes (...). Zebrafish are capable of colour vision, and in addition to cone types receptive to wavelengths of the three colours perceived also by humans (red, green, blue), they possess cones sensitive to UV light (...). Also olfaction plays an important sensory role, as zebrafish smell nutrients (amino acids), kinship cues, ovulation-inducing pheromones (steroid glucuronides), and a “Schreckstoff” (alarm substance), the glycosaminoglycan chondroitin, which is released upon injury and elicits vivid escape responses (...)."
14. ^ EZRC, KIT, & Heidelberg University (2017), hlm. 38."In the wild, a certain seasonality in reproduction seems to exist, with the mating season linked with the monsoon period. However, the presence of mature eggs in females captured in the wild all year round suggests that the observed seasonality may rather be linked to food availability and not reflect endogenous seasonal behavior. In line with this, zebrafish in captivity breed all year around under different photoperiods (12-14 hours of light). While it is still poorly understood which cues determine the choice of mating partners, a typical suite of behaviors during mating has been described76. Thus, male and female “undulate” through the water column, and the male “chases” the female, often touching her with his snout. He then “escorts” her to a spawning site, where they “circle” each other oriented head to tail. The male then “quivers”, i.e. he oscillates his body at high frequency and low amplitude close to the female over the spawning site."
15. ^ ^{a b} EZRC, KIT, & Heidelberg University (2017), hlm. 37-38."Interestingly, a recent study found that dominant-subordinate relationships seem to be relieved with increasing numbers of fish (males) kept in a tank. Thus, the number of attacks dropped when densities were increased from 2 to 6 males/liter and no attacks were observed when 10 individuals were kept per liter. Also whole body cortisol levels were lowest at a relatively high density (5 fish/l) in this experiment, indicating reduced stress levels. Consistent with these results, another recent cross-laboratory study examined the effect of stocking densities on reproductive performance, which equally can be influenced by stress levels."
16. ^ Spence et al. (2008), hlm. 16-17."The most common predatory tax a captured with zebrafish were snakeheads, Channa spp., and the freshwater garfish, Xenentodon cancila (...). Mastacembelids, which also co-occur with zebrafish, are oophagous and may be predators of zebrafish eggs and embryos, while odonate larvae may be predators of larval and juvenile zebrafish (...). Adult zebrafish are also predators of zebrafish eggs and larvae. Avian predators such as the Indian pond heron, Ardeola grayii (Sykes) and the common kingfisher, Alcedo atthis L., are also ubiquitous in the floodplains of the Indian subcontinent and may feed on D. rerio. Laboratory studies have shown that zebrafish display fright reactions in response to both visual and olfactory cues associated with predators. (...). No decline in response was detected when zebrafish were retested after a 10-day break. (...). In common with other ostariophysian fishes, zebrafish show alarm behaviours in response to a pheromone that is released as a result of injury to the epidermal cells (...). Alarm behaviours include an increase in shoal cohesion and either agitated swimming or freezing on the substrate, a decrease in feeding rate and increase in aggression. These behaviours have been interpreted as having an anti-predator function. Rehnberg & Smith (1988) demonstrated that isolated zebrafish showed an alarm response to water containing alarm substance, so the response is independent of the presence of conspecifics."
17. ^ T. S. Coe et al. (2008), hlm. 145."Genetic variation at all microsatellite loci was evaluated in terms of the number of observed alleles, allelic richness and expected and observed heterozygosity. Allelic richness was calculated using FSTAT 1.2 and expected and observed heterozygosity and Polymorphic Identification Content (PIC) were calculated using GENEPOP. The results are summarised for each zebrafish strain in Table 1. In addition, the genetic distance between individual fish, based on a pair-wise measure of allele sharing, was calculated with MICROSAT 1.5 and the neighbour-joining method was used to reconstruct a tree from the resulting distance matrix using the PHYLIP 3.6 software package. The results show that the wild fish are far more variable than the commonly used laboratory strains, for all the calculated measures of genetic variability. In particular, the strains AB (from Harvard), AB(S), TE and TL had particularly low levels of genetic variability, relative to the wild fish; allelic richness for all four strains was less than 20% of that found in the wild fish. The results also demonstrate that the same strain of fish from different sources may differ in their levels of genetic variation, as is the case for the AB strain."
18. ^ Kesalahan pengutipan: Tag <ref> tidak sah; tidak ditemukan teks untuk ref bernama :6
19. ^ Kesalahan pengutipan: Tag <ref> tidak sah; tidak ditemukan teks untuk ref bernama :9
20. ^ Kesalahan pengutipan: Tag <ref> tidak sah; tidak ditemukan teks untuk ref bernama :7