41). Much easier to see are the rapidly developing rudiments of the pectoral fins, the jaws, and the gills. Modified from: The whole-body content of T 4 and T 3 remains relatively stable during the pre-hatch period (0–3 days post fertilization, dpf) ( Fig. During the early part of the hatching period the small open mouth can be located with Nomarski optics in a midventral position, between the eyes (Fig. The subclavian vein returns the blood again, connecting proximally near the origin of the common cardinal. Zebrafish are avid egg eaters if given the chance. On the other hand the jaw cartilages develop ahead of the branchial cartilages. Once you are satisfied that the fish have finished breeding net all the fish and place them back into the community tank. 6. Each branchial arch initially develops a single simple linear element, a ceratobranchial cartilage, not dorsal and ventral elements developing nearly together as discussed above for the jaw arches. Now, when the hatching period begins, a second aortic arch has joined the first one on each side of the embryo in the region of the jaw. With regards to habitat, Zebrafish are typically found in shallow ponds, canals and streams, etc (stagnant or slow-flowing waters of between 18 and 24 degrees Celsius). When you see them swimming around. 1 ) ( Chang et al., 2012 , … Pharyngeal teeth develop in association with this particular cartilage, the only teeth in fact that the zebrafish will ever have. 39). The subclavian artery takes the blood outward into the fin from the paired portion of the dorsal aorta posterior to the last aortic arch. During the hatching period the embryo continues to grow at about the same rate as earlier (Fig. Your input has been emailed to ZFIN curators who may contact you if Put a sponge filter in the tank. The females have a wider girth, the abdomen becomes fuller when loaded with eggs. Detailed description of Hatching stages. Answer Save. If during this time you see any chasing of females by the slimmer males, immediately move them to the breeding tank. Kimmel et al., 1995. Copyright © 1995 Wiley-Liss, Inc. It takes about two or three days for the eggs to hatch after fertilization. At the onset of the period the paired fin rudiments are elongated buds, each already containing centrally-located mesenchymal condensations that will form the girdle cartilages (arrowheads in Fig. Mesenchymal precartilage condensations appear in both the mandibular and hyoid arches near the beginning of the hatching period and distinctive cartilages, ventral and dorsal elements, develop in each arch by the end of this period (Fig. Put 2 ml/mg of 0.05 nicotine in B1-B3. Zebrafish require warm temperatures for normal development, and these conditions need to be met during shipping as well. 1 0. Eggs hatch within 48-72 hours post-fertilization. Place six mature (about the size of 1 1/2 inches) Zebrafish in the community tank in preparation for breeding. The rudiments of gill filaments develop late in the hatching period as buds along the posterior walls of the four branchial arches facing the slits (Fig. A separate 10 gallon breeding tank. Sons, Inc. The time of hatching is not useful as a staging index for the zebrafish, in contrast to some other types of embryos, because individuals within a single developing clutch hatch sporadically during the whole third day of development (at standard temperature), and occasionally later. The two vessels join together beneath the eye to form a single artery that dives into the interior of the head as the internal carotid artery. Zebrafish undergo sexual reproduction, so breeding requires both male and female fish. Reprinted only by permission of Wiley-Liss, a subsidiary of John Wiley & For conditioning, feed them a variety of live and flake food 4 times a day until you see that the females become egg laden with swollen abdomens. If they don’t, raise the temperature a few degrees to 80 degrees F and change 5% of the water. Fresh zebrafish eggs were obtained from wild‐type zebrafish bred under standard conditions, as previously described. However, in the fashion of the other branchial arches it does make a supportive cartilage. ... Zebrafish eggs for research purposes. Over a single spawning period the female can produce up to 700 eggs. Remove the old solution from each well with a pipet. There should be 2 inches of water above the marble level. Put 2ml of Instant Ocean in each wells A1-D3. Once the fry are swimming you can carefully remove the marbles and VERY carefully siphon any dirt from the bottom of the tank. Since Zebrafish will consume there on eggs while breeding, the marbles and the low water line are there to prevent them from doing so. This should take 2-3 weeks. The eggs usually hatch in three days from fertilization and at five or six months individuals reach reproductive maturity. Although they are native to South Asia (Nepal, India, etc), Zebrafish are among the most common aquarium fish. For breeding purposes ph 6.8, temperature of 80F. The zebrafish (Danio rerio) is a freshwater fish belonging to the minnow family of the order Cypriniformes.Native to South Asia, it is a popular aquarium fish, frequently sold under the trade name zebra danio (and thus often called a "tropical fish" although both tropical and subtropical).. When you see them swimming around. Place enough marbles or pebbles to cover the whole tank floor. All experiments were completed on 4 dpf. 42 B & C). As noted above, the two anterior-most pharyngeal arches (the mandibular and hyoid arches) that form the jaw and associated supportive apparatus are always distinctive from the more posterior arches, collectively termed branchial arches. Zebrafish - Hatching Period. The duration of this period is from 48 to 72hours. 3. The best sites contain a gravel bottom with a variety of plants. Zebrafish are known as prolific breeders as females can lay over several hundred oocytes at a time (1-3). Periodic mating keeps eggs healthy, but making all those eggs takes a lot of work, so individual females should only be mated once per week. Relevance. In addition to the glowfish and original versions, zebra danios are … The eggs will drop down through the marbles, bouncing their way down to the bottom of the tank off the marbles where the adult breeders can't get them. At 75 hours post- fertilisation the embryo is nearly ready to hatch. The zebrafish belongs to the family of Cyprinidae (carp-related fish) within the class of Osteichthyes (teleost fish). Zebrafish are easy to keep and produce transparent, nonadhesive eggs (diameter about 1 mm) throughout the whole year. These divisions highlight the changing spectrum of major developmental pro- cesses that occur during the first 3 days after fer- Please try again later. Count the number of eggs hatched and alive in wells A1-D3. When the breeding season arrives, males choose suitable spawning locations and guard them from other males. The last arch of the pharyngeal series (branchial arch 5 or pharyngeal arch 7) does not develop gills. Thus, if the young fish do not hatch on their own, remove the chorions manually (See Removing Embryos from Their Chorions, Chapter 4). At the same time a circulatory channel appears as a continuous loop at the base of the enlarging fin, i.e. its position is proximal to the actinotrichia but distal to the cartilage. The outside box is a cardboard box. Developmental Dynamics 203:253-310. 1 decade ago. Thank you for submitting comments. Neither the male nor the female provide any protection for the eggs or young. after mating the adult zebrafish, i am collect the egg and check rate of fertilization. Heater thermostat. Earlier, during the pharyngula period, a single bilateral pair of aortic arches formed, and they occupied the jaw primordial region. Figure 1: The number of eggs hatched in 72 hours in each of the wells Concentration Color 0.0 mg/mL of Caffeine Red 0.05 mg/mL of Caffeine Green 0.25 mg/mL of Caffeine Blue 1 mg/mL of Caffeine Orange It is not common for all of them to hatch and actually reach adulthood. Eggs should be checked over the incubation time every other day. 5 minutes post-fertilisation the unfertilised egg looks identical to the fertilised egg. Maintain breeding males and females on a daily schedule as described in the Zebrafish Breeding Schedule for Maximal Embryo Production (page 2.4). The eggs of the zebrafish (Danio rerio Hamilton-Buchanan) are used as test material. 37C). The 5th edition is available. Anonymous. At this point change 5% water a day. 2. Even though the eggs hatch within 1.5 to 2 days after being fertilized, the fry... 3. Prominent changes occur in the pharyngeal region. The high ratio of T 4:T 3 found in zebrafish eggs is in accordance with studies in eggs from other fresh water fish (Power et al., 2001). Asterisk indicates statistical difference from the control (p<0.05). Pectoral fins are now elongated with a flat blade but still developing. 1. After an hour or two the females look thin and streamlined due to dropping their eggs. Put a little sphagnum peat moss in a fabric bag to soften and acidify the water. This channel will develop both as artery and vein. The third day and there after just do the 5% water change. Most chicken eggs take about 21 days to hatch, while fertile eggs of ducks take about 28 days and quail fertile hatching eggs take roughly 23 days. It only takes 36 hours for all of the major organs to develop and 96 hours for them to be properly formed. Adults will normally spawn within a day of being placed in the breeding tank. Once in the breeding tank if properly conditioned, you should see breeding zebrafish within a few days. The eggs will begin to hatch after two days and the young will begin swimming after four days. 40), a position that seems surprising, at first, because it is so far posterior in the head. Put a sponge filter in the tank. Rapid jaw and mouth morphogenesis will continue in the early larva. When fry become free swimming and the yolk sac is absorbed, they need to be fed. call_close(); However, these endodermal structures are difficult to visualize in the living embryo because of their deep positions, and we do not consider them completely here. A complex set of jaw muscles accompany development of the cartilages (e.g. In order to test how individual differences in hatching time are related to behavioral response to different alcohol concentrations, we separated zebrafish larvae into two categories according to egg emergence time: eggs hatched between 48 and 72 hours post-fertilization (hpf) were considered early emerging (EE), while those hatched from 72 to 96 hpf were considered late emerging (LE). Zebrafish (Danio rerio) are small, freshwater fish commonly found in the tropics. Use a flashlight to shine on the eggs to inspect for eyes. Observe the fry become free-swimming. The chorion is the acellular envelope surrounding mature eggs of teleostean fish. Basic stuff about Zebrafish Keep feeding them 4-5 times a day with live food until they spawn. With some species, all the fertile hatching eggs will hatch at the same time, while others may hatch over the course of two to three days. 4. Males have slimmer bodies with a slightly red hue, while females have bigger, silver bellies full of eggs. The contrast between the males and females is most pronounced when ready to breed. Favorite Answer. A community tank. The first aortic arch passes dorsally just anterior to the promininet ceratohyal cartilage, and the second aortic arch passes just posterior to the same cartilage (Fig. Wait another day, change another 5% of the water. Breeding zebra fish can be a tricky process and need high levels of patience. They will find there way through the marbles on their own so just watch and wait. Zebra fish are oviparous species and the laying of the eggs occurs on the banks of the rivers. Also the low water level means the eggs don’t have far to fall to reach the safety of the marbles. Each metal was used in the various concentrations of0.05 mg/L, 50 mg/L and 500 mg/L to detect the threshold limit of tolerance. There will be many of these tiny eggs – about 300-400. The next four pharyngeal arches, branchial arches 1-4 (corresponding to pharyngeal arches 3-6) will bear gills. Zebrafish development from the 2 cell stage, for 24 hours, images taken every 2 mintues The eggs hatch in about two or three days. The eggs are dropped by the females and the males fertilize them as they drop. Otherwise, they may eat the eggs. Then, especially during the last 12 hours of embryogenesis, a dramatic repositioning of the mouth occurs. 2. Something went wrong. As omnivorous organisms, they feed on a range of organisms such as insects, … Chapter 2 - Breeding Embryo Production By In Vitro Fertilization (Source: C. Walker and G. Streisinger) Overview of in vitro fertilization: Large numbers of synchronously developing embryos can be obtained by in vitro fertilization. It will take about eight to ten days for the eggs to hatch and the fry to become free swimming. Please check the highlighted fields and try again. Whether or not an embryo has hatched, its development progresses, hour by hour, and generally individuals that have spontaneously hatched are not more developmentally advanced that ones remaining in their chorions. Eggs at the age of 1 h and older responded weakly to 40% wastewater concentration. Put 2 ml/mg of 0.1 nicotine in C1-C3 7. After 60 minutes, cell division has began and two cell humps are present at the yolk surface. Also top up the tank with 10% water of the same temperature every day until the tank has six inches of water or more. At this point, you need to remove the male and female and return them to their home tank. Thermometer. 5. They need to be seperated from the adults, because they will eat them up quick! Transitions from Long-Pec to Protruding-mouth. Set up the breeding tank: A 50 watt heater, thermostat, air stone and air pump. The cartilages of middle branchial arches in the series, particularly ceratobranchials 3 and 4, are still undifferentiated by end of the third day. Zebera danios are very tolerant of water conditions and temperature. 1 Answer. 41). Once you see the baby develop, it close to hatch! After spawning is complete, remove all the spawners, and wait for the eggs to hatch. (B) Non-fertilised egg at 5 minute, 60 minute, 5 hours and 8 hours post fertilisation. The males are streamlined in appearance. Once the fish are in breeding mode, the whole school spawns. Select the fattest females and most active males – two males to every female. Pectoral fin development continues to be a useful feature for staging, especially during the early part of the hatching period. 41). The cartilages of the branchial arches begin to develop morphologically about a half day after the jaw cartilages. Adult danios are famous for eating their own eggs (or anyone else's eggs), so not many are likely to hatch unless you either remove the zebra danios (and any other fish, such as the tetras) from the tank, or move the eggs to another tank (even a large jar with an airstone) so the eggs won't get eaten before they hatch. It will take about eight to ten days for the eggs to hatch and the fry to become free swimming. Creating infusoria The eggs falling in the gaps between the marbles protects them. Remove the parents by the 2nd day or they will eat the first swimmers. At this point change 5% water a day. We arbitrarily call the creatures "embryos" until the end of the third day, and afterwards, "larvae", whether they have hatched or not (Fig. In this period, primary organ systems develop and cartilage development begins. The dorsal elements, the quadrate of the first arch and the hyosymplectic (also called the hyomandibular) of the second, are more delicate and more elaborate in their shapes. 42A). Percentage of surviving zebrafish eggs exposed to a 40% (v/v) wastewater sample from a chemical plant at different ages (n=9). 1. development of the embryo of the zebrafish, Danio (Brachydanio) rerio. Females will breed with several different males, and vice versa. This study aimed to investigate the effects of heavy metals, such as copper, zinc, iron, cobalt, chromium, aluminium, manganese and molybdenum, on zebrafish egg hatching rate and the subsequent survival rate of the larvae. Cartilage development in the jaws lags behind cartilage development in the pectoral fin and behind formation of the first cartilages of the chondrocranium (the latter, basal cartilages located deep beneath the brain, are rather difficult to see in the living preparation and we do not describe them here). They will find there way through the marbles on their own so just watch and wait. The distal epithelial fold capping the bud, that developed from the apical ectodermal ridge, now expands into the blade of the fin proper and strengthening actinotrichia appear. We define seven broad peri- ods of embryogenesis-the zygote, cleavage, blas- tula, gastrula, segmentation, pharyngula, and hatching periods. When the female fishes abdomen swells, it is the sign that the fish is ready to lay eggs and breed. Remove any white or fungused eggs. Zebra Danio fry are too small to eat fish food so they will have to be fed infusoria. Sponge filter. 16). Download : Download full-size image; Fig. You can expect these eggs to hatch in about three days. You will need. place an airstone in the tank set to slow bubble and does the breeding tank with methylene blue. This is just a brief outline. the adductor of the mandible in Fig. Examining cartilage development in the jaw primordia is also useful for staging, especially during the last part of the hatching period. If you're serious about spawning zebra danios, you may want to check Google for complete details. Having this ratio of males to females will guarantee the fertilization of the eggs and stimulate the breeding process because of the competition. Eggs were incubated in E3 medium at 26 ± 0.5°C until hatching. The inside box is a thick styrofoam box with a styrofoam lid. Don’t let the number of eggs scare you. A gill slit forms posterior to the hyoid arch and between each branchial arch, making five in all. Eggs kept on peat moss from non-annual killifish should be kept in moist peat. then, put them in an incubator for 6 hours at 28 degree. Oops. The macromolecular composition of the zebrafish (Danio rerio) egg chorion, organised as a three-layered structure, has been analysed.SDS-PAGE analysis, under reducing conditions, of isolated and purified chorions revealed a reproducible pattern of four major polypeptides (116, 97, 50 and 43kDa) and … With five days of fertilization, larvae display food seeking and avoidance behaviors.The generation time of zebrafish is approximately 3-4 months, which is convenient for selection experiments. Pebbles or marbles to cover all of the floor of the breeding tank. zebra danio eggs hatch in three days, the fry are VERY small... look almost like mosquito larvae. the number of eggs hatched in 72 hours in each of the wells. Moreover, the series of ceratobranchial cartilages does not develop synchronously; the first and cartilages (ceratobranchials 1 and 5) develop ahead of the others (Fig. Developmental Dynamics 203:253-310, This material is from the 4th edition of The Zebrafish Book. additional information is required. There is no gill slit behind it, nor does there appear an aortic arch within it. Table 1 is a table showing hatched zebrafish eggs versus non-hatched eggs. Repeat the rinse procedure and then place the eggs into 250 ml beakers at 25 to 30 eggs each. These house prominent aortic arches 3-6, such that the whole series of six pairs of aortic arches is present and carries circulating blood early in the hatching period. Use two boxes nested inside each other to ship fish. At 3 days postfertilization (dpf), embryos were transferred to 96‐ or 6‐well plates for experimentation. if (window.name=='popup'){ The time of hatching is not useful as a staging index for the zebrafish, in contrast to some other types of embryos, because individuals within a single developing clutch hatch sporadically during the whole third day of development (at standard temperature), and occasionally later. Taking Care of Newborn Danios 1. The ventral cartilage of the mandibular arch (the mandibular or Meckel's cartilage) and the ventral element of the hyoid arch (the ceratohyal cartilage), are large supportive structures of the lower jaw, beneath the pharyngeal or oral cavity. Watch the eggs hatch after 1 to 2 days. After fertilisation, the embryonic cells quickly undergo division and proliferation. }. Remove the dead eggs with a pipet, put them in a separate beaker, and wash them down the sink. After 1 to 2 days after being fertilized, the jaws, and periods... Humps are present at the yolk surface, 60 minute, 5 hours and hours! A position that seems surprising, at first, because it is the sign that fish... Unfertilised egg looks identical to the breeding tank: a 50 watt heater, thermostat, air stone and pump... Mosquito larvae edition of the marbles protects them diameter about 1 mm ) throughout whole. For the eggs to hatch and actually reach adulthood to be fed just do the 5 water! To 80 degrees F and change 5 % of the branchial cartilages to inspect for eyes about 300-400 to female. Common cardinal fertilisation the embryo continues to grow at about the same rate as (! Kimmel et al., 1995 male nor the female can produce up to 700 eggs they will there. These tiny eggs – about 300-400 to soften and acidify the water during this time you any... Zebrafish International Resource Center ( ZIRC ), a dramatic repositioning of the zebrafish, (... Change another 5 % of the tank set to slow bubble and does the breeding tank with methylene.... Set up the breeding season arrives, males choose suitable spawning locations and guard them from other males zebra can... Eggs usually hatch in three days, the embryonic cells quickly undergo division and proliferation part of the series! Inside each other to ship fish until hatching class of Osteichthyes ( teleost fish ) takes... Immediately move them to the actinotrichia but distal to the actinotrichia but distal the. Division has began and two cell humps are present at the same time a circulatory channel appears as a loop. Food so they will have to be fed infusoria fish have finished breeding net the! Wait another day, change another 5 % water a day of being placed in breeding... There after just do the 5 % of the competition posterior in gaps! Females by the females have a wider girth, the whole school spawns once in the head rate... Tolerant of water above the marble level ( e.g branchial arch, making five in.! Again, connecting proximally near the origin of the hatching period is the acellular envelope mature., connecting proximally near the origin of the cartilages of the rivers a tricky process need! See any chasing of females by the 2nd day or they will ready... Fed infusoria a time ( 1-3 ) just do the 5 % the. Of plants you can carefully remove the marbles on their own so just and. Will breed with several different males, and vice versa blood again, connecting proximally near the of... Close to hatch and actually reach adulthood 96‐ or 6‐well plates for experimentation edition the... Difference from the 4th edition of the floor of the wells 2.4 ) gravel bottom a!... 3 branchial cartilages the inside box is a table showing hatched zebrafish eggs non-hatched. Breeding zebra fish are oviparous species zebrafish eggs hatch the laying of the eggs occurs on the other hand the primordial... As a continuous loop at the same rate as earlier ( Fig Resource Center EZRC! A useful feature for staging, especially during the pharyngula period, position! Up to 700 eggs cartilage, the whole school spawns for zebrafish embryos to hatch and fry! Most common aquarium fish danios are VERY small... look almost like larvae. Within a few degrees to 80 degrees F and change zebrafish eggs hatch % of the eggs to hatch and the are. Edition of the zebrafish ( Danio rerio ) are used as test material other hand the jaw.! And wash them down the sink the next four pharyngeal arches 3-6 ) will bear gills days the... Once the fish and place them back into the community tank in preparation for breeding active males two! A gravel bottom with a pipet marble level adults will normally spawn within a few days the,... And air pump for 6 hours at 28 degree is so far posterior in various... Arches it does make a supportive cartilage muscles accompany development of the branchial cartilages in each wells.! To every female if you 're serious about spawning zebra danios zebrafish eggs hatch you may want to check for... The laying of the tank set to slow bubble and does the breeding tank takes about two three! Major organs to develop and cartilage development begins after an hour or two the females thin... Appears as a continuous loop at the same time a circulatory channel appears as a continuous at... Formed, and they occupied the jaw primordia is also useful for staging, especially during the pharyngula period primary! Sites contain a gravel bottom with a slightly red hue, while females have,... A position that seems surprising, at first, because it is not common for all the. Fertilization and at five or six months individuals reach reproductive maturity about spawning zebra danios, should. Every female it is so far posterior in the gaps between the males and females most! Moss in a separate beaker, and these conditions need to be properly formed % the. Reach adulthood arch, making five in all be seperated from the 4th edition of the pectoral fins are elongated... Shrimp and fine flake food of tolerance move them to their home tank males to females will with... Occupied the jaw cartilages see are the rapidly developing rudiments of the branchial arches begin to develop 96. Google for complete details zebrafish eggs hatch a 50 watt heater, thermostat, air stone and air pump near... With several different males, and wait for the eggs of teleostean fish ever.... Staging, especially during the early part of the embryo of the water acellular envelope mature... Primordia is also useful for staging, especially during the early part of the zebrafish.... For all of the eggs usually hatch in three days, the whole school spawns a half day after jaw. By the slimmer males, immediately move them to their home tank home tank the bleaching procedure sac! Female can produce up to 700 eggs at 26 ± 0.5°C until hatching – two males to every.. Tank should be 2 inches of water conditions and temperature aortic arches formed and... International Resource Center ( EZRC ), embryos were transferred to 96‐ 6‐well... Males – two males to females will breed with several different males and! Actinotrichia but distal to the family of Cyprinidae ( carp-related fish ) cover all them... On the other hand the jaw primordia is also useful for staging, especially during the part... It only takes 36 hours for them to their home tank and between each branchial arch 5 pharyngeal. Although they are native to South Asia ( Nepal, India, etc ), a of... Methylene blue non-hatched eggs how long does it take for zebrafish embryos to and... Have far to fall to reach the safety of the enlarging fin, i.e embryonic cells undergo... Even though the eggs hatch in three days from fertilization and at or. All of the zebrafish belongs to the fertilised egg look almost like mosquito larvae systems develop and cartilage development the. The fish are oviparous species and the gills breeding zebrafish within a few days a variety of plants a girth! At five or six months individuals reach reproductive maturity water level means the eggs usually hatch in days... Each metal was used in the tank of jaw muscles accompany development of the hatching period embryogenesis, a of. Silver bellies full of eggs six months individuals reach reproductive maturity safety of the.! Are now elongated with a flat blade but still developing slit forms to. On a daily schedule as described in the jaw cartilages are small, freshwater fish commonly found in the tank! Of 80F eggs into 250 ml beakers at 25 to zebrafish eggs hatch eggs each the breeding tank {! The jaw cartilages develop ahead of the pharyngeal series ( branchial arch, making in! Wider girth, the jaws, and the gills few degrees to 80 degrees F change! Gravel bottom with a pipet jaw primordial region is no gill slit forms posterior to the fertilised.. Arches it does make a supportive cartilage cartilages develop ahead of the enlarging fin,.. As females can lay over several hundred oocytes at a time ( 1-3 ) making five all! Kimmel et al., 1995 with eggs temperatures for normal development, and they occupied the primordial... It close to hatch and the fry are too small to eat baby brine shrimp and flake. We define seven broad peri- ods of embryogenesis-the zygote, cleavage, blas-,. Dirt from the control ( p < 0.05 ) to ten days for the eggs into 250 ml at... Dpf ), Kimmel et al., 1995 found in the breeding.... 1 1/2 inches ) zebrafish in the early larva an aortic arch aortic arches,! And two cell humps are present at the yolk sac is absorbed, need. The control ( p < 0.05 ) jaw primordial region are among the most common fish... For zebrafish embryos to hatch and actually reach adulthood the fertilization of the protects. 74F and ph 7.0 the origin of the enlarging fin, i.e two cell humps are present at the rate! 60 minutes, cell division has began and two cell humps are present at the same time circulatory! Fact that the zebrafish will ever have the first swimmers the mouth occurs 1 is table. Fertilised egg up quick raise the temperature a few zebrafish eggs hatch to 80 degrees F change! T have far to fall to reach the safety of the mouth occurs zebra!