Study On Feeding Behavior And Allometric Development Of Juvenile Lined Seahorses

Hippocampus erectus,which is named as "south ginseng" in China,is the main breed of domestic breeding and it is a precious marine animal with scarce medicinal resources,The sharp contradiction between market supply and demand leads to the shortage of wild resources of H.erectus,and the core problem of artificial cultivation is the low survival rate in seedling stage.In this experiment,the feeding behavior of juvenile at the age of 1-30 days(body height: 9.22~43.16mm)was observed and recorded through behavioral research,the feeding ability and the allometric development at the juvenile stage were studied by analyzing feeding behavior parameters.Finally,the degree of consummation of feeding function was discussed by combining the development of muzzle bone,vision and digestive system.The results are as follows1.The feeding behavior of H.erectus juvenile is divided into two parts: attack and ingestion,and attack is divided into four stages: search,positioning,adjustment and attack.Ingestion involves only one swallowing process.Under feeding state,attack distance(AD),attack speed(AS),feeding aperture(FC),daily intake(DTFA)and success rate of feeding(SFR)increase with development.Feeding efficiency(FE)increases rapidly after 14 days of age,and reaches 0.0856mg/s at 30 days of age.2.According to the observation of muzzle bone development,the tubular snout of hippocampal larvae is composed of maxilla,outer pterygoid,square bone,condyles and lingual horn bone.During the feeding process,the bait entered the tubular nose from the distended maxilla,and the rostral bone was not completely hardened at the age of 1-7 days.During the feeding process,the rostral tube could be dilated.After the age of 14 days,the bone of the muzzle was basically fully developed and the bone was hardened,and the feeding ability began to increase.3.Observation of the development of eyeball structure showed that at birth,the H.erectus had relatively complete eyeball structure,complete retinal pigment deposition,and cone cells and rod cells existed between the pigment layer and the external membrane,the retina has 10 layers,and only the thickness and diameter of the retina increase with the development of the larvae.4.Observation of the development of the digestive system showed that when the young hippocampus left the pouch,the mouth and anus were in an open state,and there was a small amount of yolk around the intestinal tract.According to the morphology,the digestive tract could be divided into four parts: oropharyngeal cavity,anterior intestine,middle intestine and posterior intestine.The anterior intestinal mucosa is rich in cells and secretes neutral mucus.The hippocampus has no stomach,and the valves separate the anterior intestine and midgut.As it grew,its structure and function improved.after 10 days of age,the intestinal tract began to curve and the adipose tissue around the internal organs began to form.The intestinal tract completed the curve and rotation in the abdominal cavity,forming multiple loops.The digestive tract further grew,and the digestive tract was basically fully developed by 30 days.5.As a result of allometric growth,hippocampal larvae showed a growth inflection point at the age of 10 days and a growth rate of 1.42mm/d after the age of 10 days.All the functional organs showed the characteristic of allometric development,the important organs related to movement,food intake and sensation are all developed preferentially,which was beneficial to avoid the enemy and improve the success rate of feeding in the unfavorable natural environment at the early stage.