Source of content: general zoology lab guide.
Operation method
Experiments on the external and internal anatomy of the carp (Cyprinus carpio)
Principle
1. to acquire the main features of scleractinian fishes and the morphological and structural characteristics of fishes adapted to aquatic life through structural observation of carp. 2. to learn the basic manipulation of internal dissection of scleractinian fishes. 3. to learn the basic techniques of internal dissection of scleractinian fish.
Materials and Instruments
Carp. Skeletal specimens. Move The tips of the scissors should not be inserted too deeply when cutting the body wall, but should be cocked upward to avoid injury to the viscera; before removing the left body wall muscle, care should be taken to peel the peritoneum of the body cavity away from the body wall with forceps so as not to damage the kidneys that cover the anterior and posterior swim bladder chambers and the cephalic kidney that is located immediately posterior to the head. Common Problems I. Demonstration Shark skull For more product details, please visit Aladdin Scientific website.
Dissecting Instruments Dissecting Plates Dissecting Mirrors Mane Cotton Petri dishes
I. Appearance
The body of the carp (or crucian carp) is fusiform, slightly laterally flattened, with a gray-black back and a nearly white belly. The body can be distinguished into 3 parts: head, trunk and tail.
1. Head
From the end of the muzzle to the posterior edge of the gill cover bone is the head.
The mouth is located at the front of the head (the endoparietal position), and there are two tentacles on each side of the mouth (Carassius auratus does not have tentacles), what is the function of the tentacles?
On the back of the muzzle there is 1 pair of nostrils through which the bristles are probed, does the nasal cavity lead to the oral cavity? Is it involved in the respiratory process?
1 pair of eyes, located on both sides of the head, large and round in shape. After the eyes on both sides of the head for the broadly flattened gill cover, gill cover the posterior edge of the gill cover membrane membrane, by covering the gill holes.
2. Trunk and tail
From the posterior margin of the gill covers to the anus is the trunk; from the anus to the last vertebrae at the base of the caudal fin is the tail.
The carapace and tail are covered with rounded scales arranged in an imbricate pattern, with a thin layer of epidermis covering the scales, so touch the fish's body surface with your hand. What is the purpose of this?
Both sides of the carapace from the back edge of the gill cover to the caudal part, each has a dotted line structure arranged by small holes in the scales, which is the lateral line; the scales that are crossed by the lateral line holes are called lateral line scales, what is the function of the lateral line?
The body has dorsal and ventral fins, one dorsal fin, longer, about 3/4 of the torso; one anal fin, shorter; the end of the caudal fin is concave and divides into two proportional lobes, which is orthotropic; one pair of pectoral fins is located on the left and right sides behind the gill cover; and one pair of ventral fins is located after the pectoral fins and before the anus, which is in the ventral position of the abdominal fins.
The anus is located immediately in front of the base of the beginning of the anal fin, and there is a cloaca immediately after the anus.
Internal anatomy and observation
Place fresh carp (or crucian carp) on the dissecting plate, make its abdomen upward, use scissors to cut a small opening in front of the anus and the body axis in the vertical direction, insert the tip of the scissors into the incision, and cut along the abdominal midline forward to the mandible through the middle of the ventral fins; make the fish lie down on its side, with its left side upward, and cut from the opening in front of the anus to the spine to the dorsal side, and then along the spine to the posterior margin of the gill cover, and then along the posterior margin of the gill cover to the mandible, and then remove the muscles of the left side of the body wall, so as to expose the heart and internal organs. Exposed.
The blood and tissue fluid around the organs were swabbed with cotton and placed in a dissection tray in salty water for observation.
1. In situ observation
In front of the abdominal cavity, a small cavity behind the last pair of gill arches is the pericardial cavity, which is separated from the abdominal cavity by the diaphragm.
The heart is located in the pericardial cavity.
In the abdominal cavity, ventral to the spine, is the white sac-like swim bladder covering a triangle of dark red tissue between the anterior and posterior swim bladder chambers, part of the kidney.
Ventral to the swim bladder are the elongated gonads, the cream-colored spermathecae in males and the yellow ovaries in females.
The coiled ducts on the ventral side of the abdominal cavity are the intestinal tubes, and in the mesentery between the tubes are the dark red, diffusely distributed hepatopancreas.
An elongated reddish-brown organ between the intestinal ducts and the hepatopancreas is the spleen.
2. Reproductive system
It consists of the reproductive glands and the reproductive ducts.
(1) Reproductive glands
The reproductive glands are covered with a very thin membrane.
Males have one pair of spermathecae, which are pure white and flattened and sac-like when sexually mature; when sexually immature, they tend to be light red, often asymmetrical and fissured from side to side.
Females have one pair of ovaries, pale orange-yellow and long banded when sexually immature; when sexually mature they are yellowish-red, long cystic, filling almost the entire abdominal cavity, and containing many small shaped oocytes.
(2) Reproductive ducts
A thin tube extending backward from the membrane on the surface of the gonads, the vas deferens or oviduct. It is very short, and the posterior ends of the right and left tubes are united, leading into the cloacal sinus, which opens out of the body with a cloacal orifice.
After observation, the left gonad is removed so that the other organs can be observed.
3. Digestive system
The digestive system consists of the mouth, pharynx, esophagus, intestines and anus, as well as the liver, pancreas and gallbladder. The esophagus, intestine, anus and gallbladder were mainly observed here.
The coiled intestinal tubes are unfolded with blunt-tipped forceps.
(1) Esophagus
The most anterior part of the intestinal tube joins the esophagus, which is very short, and has a swim bladder tube passing through the back of it, and this serves as the point of demarcation between the esophagus and intestines.
(2) Intestine
The length of the intestine is two to three times the length of the body. What is the correlation between the length of the intestine and the appetite? The first 2/3 of the intestine is the small intestine, the thinner posterior portion is the large intestine, and the last portion is the rectum, which opens anteriorly with the anus at the base of the anal fin.
(3) Gall bladder
The gallbladder is a dark green oval sac located on the right side of the anterior part of the intestinal tract. It is mostly buried in the hepatopancreas and leads into the anterior part of the intestines through the bile ducts.
4. jacks
The bladder is a silvery-white gelatinous sac located on the dorsal surface of the alimentary canal and extends to the posterior end of the abdominal cavity, where it is divided into an anterior and posterior chamber. It is divided into two chambers, the anterior and posterior. The anterior chamber gives rise to a long, thin swim bladder tube, which leads into the dorsal wall of the esophagus. What are the functions of the swim bladder?
Remove the swim bladder after observation so that the excretory system can be observed.
5. Excretory system
It consists of 1 pair of kidneys, 1 pair of ureters and 1 bladder.
(1) Kidneys
Immediately adjacent to the dorsal wall of the abdominal cavity on both sides of the midline, for the reddish-brown narrow organ, in the swim bladder of the anterior and posterior chambers of the junction of the kidneys to expand or its widest point.
The anterior end of each kidney expands laterally towards the front and increases in size as a cephalic kidney, which is an anthropomorphic lymph gland.
(2) Ureter
A thin tube, the ureter, passes out of each kidney at its widest point, and travels posteriorly along the dorsal wall of the abdominal cavity, where the two tubes join near the end to pass into the bladder.
(3) Bladder
The bladder is formed by the slightly enlarged sac formed by the confluence of the posterior ends of the two ureters, the end of which is slightly thin and opens into the cloacal sinus.
6. Circulatory system
The heart is the main observation, and the vascular system is omitted. The heart is located in the pericardial cavity between the two pectoral fins and consists of 1 ventricle, 1 atrium and venous sinus.
(1) Ventricle
The ventricle is located in the center of the pericardial cavity and is light red in color, with a white, thick-walled, conical sphere at its anterior end, which is the arterial sphere.
From the arterial bulb, a thicker blood vessel emanates forward, the abdominal aorta.
(2) Atrium
It is located on the dorsal side of the ventricle, dark red in color and thin and sac-like.
(3) Venous sinus
Located at the posterior end of the atrium, dark red in color, with very thin wall, not easy to observe.
After the above observations, scissors are inserted into the mouth, the corners of the mouth are cut, and the gill covers are cut along the posterior margins of the eyes to expose the mouth and gills.
7. Oral cavity and pharynx
(1) Oral cavity
The oral cavity is synthesized by the upper and lower jaws, the jaws are edentulous, the dorsal wall of the oral cavity consists of thick muscles with mucous membranes on the surface, and there is an inactive triangular tongue in the posterior half of the cavity floor.
(2) Pharynx
After the oral cavity for the pharynx, its left and right sides have five pairs of gill slits, adjacent gill slits between the birth of gill arches, a total of five pairs.
The fifth pair of gill arches specializes into the pharyngeal bone, which bears pharyngeal teeth on its inner side. The pharyngeal teeth are opposed to the ventral horny pads of the basioccipital bone on the back of the pharynx, and the two are capable of crushing food.
8. Gills
Gills are the respiratory organs of fish. The gills of carp (or crucian carp) consist of gill arches, gill rakers and gill plates, with degenerated gill intervals.
(1) Gill arch
Located within the gill cover, both sides of the pharynx, a total of 5 pairs.
There are gill rakers on the concave surface of the inner edge of each gill arch; the first to fourth pairs of gill arches have two gill lamellae side by side on the outer edge of the gill arches, and the fifth pair of gill arches have no gill lamellae.
(2) Gill rakers
Rows of triangular projections on the concave surface of the inner margin of the gill arches.
The 1st to 4th gill arches each have 2 rows of gill rakers, alternating from side to side, the outer gill rakers of the 1st gill arch are longer.
The 5th gill arch has only 1 row of gill rakers.
What is the function of gill rakers?
(3) Gill lamellae
Thin, flaky, reddish in color when fresh.
Each gill is called a half gill, and two half gills growing on the same gill arch are collectively called Gills are called whole gills.
Cut off a whole gill, put it in a petri dish with a small amount of water, and observe it under a dissecting microscope.
Visible gill slice consists of many gill filaments, each gill filament on both sides of the gill and many raised gilllets, gilllets on the distribution of rich capillaries, is the place of gas exchange. When the gill arches were cut transversely, a degenerated gill septum was visible between the 2 gill lamellae.
9. Brain
Cut under both orbits, cut the back bone of the head in the direction of the longitudinal axis of the body; then cut transversely between the two ends of the two longitudinal incisions; carefully remove the back bone of the head, and use a cotton ball to aspirate the silvery shiny cerebrospinal fluid, and the brain will be revealed.
Observation from the back of the brain
(1) Telencephalon
It consists of the olfactory brain and the cerebrum.
The cerebrum is divided into the left and right hemispheres, each of which is located in the front of the brain in the form of a small ball, the tip of which extends a rod-shaped olfactory stalk, which ends in an oval-shaped olfactory bulb, and which constitutes the olfactory brain.
(2) Midbrain
It is located after the telencephalon and covers the back of the mesencephalon.
It is larger, and is favored to both sides by the cerebellar flaps, each of which has a half-moon shaped protrusion, also known as the optic lobe.
(3) Cerebellum
Located behind the midbrain, it is a globular body with a smooth surface, and the cerebellar valve protrudes into the midbrain in front of it.
(4) The medulla oblongata
It is the last part of the brain and consists of one facial lobe and one pair of vagus lobes. The facial lobe is in the center and its front part is covered by the cerebellum, so that only its back part can be seen, while the vagus lobes are larger and are paired left and right, on the back sides of the cerebellum. The posterior part of the medulla oblongata narrows and connects to the spinal cord.
Skeletal System
Skeletal specimens of carp (or crucian carp) were taken as a whole and dispersed, and the skull, spine and appendicular skeleton were observed.
1. Skull
The skull has a depressed nasal cavity dorsally at the anterior end and orbits centrally on both sides.
It can be divided into two main parts for observation: the cerebral cranium and the pharyngeal cranium.
(1) Cerebral cranium
The number of bone fragments is large.
From anterior to posterior, it can be divided into 4 zones for observation.
①Nasal zone
Located at the anterior-most end, the area surrounding the nasal capsule.
The main bone fragments are: 1 middle sieve bone, located in the center of the anterior end, slightly triangular; 1 pair of lateral sieve bones, located in the posterior-lateral side of the middle sieve bone, irregularly triangular, with the tip facing backward; there is also 1 anterior sieve bone in front of the middle sieve bone.
② Butterfly region
Immediately after the nasal region, it surrounds the orbit.
It consists of the following bones: the pterygoid, which forms the medial wall of the orbit, and the orbital pterygoid, which is located in front of it and is slightly rectangular in shape, as well as the six periorbital bones that surround the orbit on the lateral side of the brain and skull.
③Auricular region
Anteriorly attached to the pterygoid region, it surrounds the ear capsule.
The main ossicles are 1 pair of pteropodial ossicles, located on the posterior-lateral aspect of the frontal bone; 1 pair of pteropodial ossicles, located on both sides of the parietal bone, which are long and irregular; and 1 pair of epipodial ossicles, which are small, capitulum-shaped ossicles located on the posterior aspect of the parietal bone.
④ Occipital region
The last part of the cranium of the brain.
It consists of four bone fragments surrounding the foramen magnum of the occipital bone, including a supraoccipital bone located centrally at the posterior end of the skull, with a higher sphenoidal protrusion extending dorsally and centrally; an extra-occipital bone ventral to the supraoccipital bone and on either side of the foramen magnum of the occipital bone; and a basioccipital bone located centrally at the posterior end of the ventral aspect of the brain-cranium, which has a concave, sub-shield-like ventral surface, which is in close proximity to the corneal cushion.
Then viewed from the dorsal and ventral surfaces of the cerebral cranium.
⑤ Dorsal view of the cranium
From the front to the back, there are one pair of nasal bones on both sides of the anterior sieve bones, one pair of frontal bones, which are attached to the middle sieve bones and are slightly rectangular in shape, and one pair of parietal bones behind the frontal bones, etc. The dorsal view of the cranium is from the front to the back.
(6) Ventral view of the cranium
From the front to the back, there is one plow bone, which is slightly "Y"-shaped; and one parasphenoid bone, which is an elongated bone, constituting the bottom wall of the cerebral box.
(2) Pharyngeal Cranium
It is located below the cranium and surrounds the anterior end of the alimentary canal. It consists of symmetrical and segmented bones, including the maxillary arch, lingual arch, gill arch, and the gill cover bone system.
①Maxillary arch
The maxillary arch is the bone sheet that constitutes the upper and lower jaws.
The upper jaw consists of a pair of premaxillae located in the anterior most part of the upper jaw, a pair of slightly curved maxillae behind the premaxillae, and the pterygoid and subtriangular square bones behind the maxillae.
The mandibular portion consists of the odontoid, articular, and coracoid bones. The dentary is a rod-shaped bone at the anterior edge of the mandible, and its posterior end extends upward, connecting the jaws; the articular bone is located behind the dentary, and is irregular in shape, associated with the square bone; the coracoid bone and the articular bone fit together and are not easily separated.
②Tongue arch
It is situated at the back of the maxillary arch.
Observing the medial side of the anterior gill cover bone, there is a flat sword-shaped bone piece, forming the posterior wall of the eye socket, which is the lingual jaw. The dorsal end of the lingual jaw is articulated with the lateral depression of the cranial side of the brain, and the ventral end is connected to the phalanx by a small continuation of the bone, what is its function? The lingual arch is formed by the lingual maxilla and its ventral series of blocks, and the tongue is supported by the basal hyoid bone in the center of the abdomen.
(3) Gill arch
A piece of bone that supports the gills.
Observe the gill arch specimen, carp (or crucian carp) has 5 pairs of gill arches.
The first gill arch is divided into five bony segments from dorsal to ventral, including pharyngeal gills, upper gills, angular gills, lower gills and basal gills. The 5th gill arch is specialized into pharyngeal bone, which has 3 rows of pharyngeal teeth on the inner edge, toothed (only 1 row of pharyngeal teeth in Carassius auratus).
④Gill cover bone system
Located on both sides of the posterior part of the skull, each side consists of 4 gill cover bones and 3 gill bar bones.
2. Spine and ribs
The spine consists of a series of vertebrae, divided into two parts: the carapace vertebrae and the caudal vertebrae.
(1) Carapace vertebrae and ribs
The structure of the vertebrae after the 5th vertebra is observed and consists of the following parts
①Vertebral body
The central part of the vertebrae is concave at the front and back, and it is a biconcave vertebrae.
②Vertebral arch
The back of the vertebral body is bow-shaped.
③Vertebral spine
A backward sloping protrusion in the center of the dorsal arch of a vertebra.
④Transverse vertebral process
The projections on either side of the vertebral body are transverse processes.
⑤Articular synchondrosis
There is a pair of small, pointed projections anterior to the base of the vertebral arch called the anterior synchondrosis, and a pair of projections posterior to the vertebral body called the posterior synchondrosis. The anterior and posterior articular processes of two neighboring vertebrae are related.
(6) Vertebral foramen
The hole between the vertebral body and the vertebral arch through which the spinal cord passes.
(7) Ribs
From the 5th to the 20th vertebrae, there are long ribs, the dorsal end of each rib is associated with the transverse process of the vertebrae, and the ventral end is free. What is the function of the ribs?
(2) Caudal Vertebra
The caudal vertebrae have vertebral bodies, vertebral arches, medullary spines, and articular eminences; the transverse processes of the vertebral bodies protrude ventrally into the vein arches; the foramina in the middle of the arches are crossed by the caudal arteries and veins; and the vein arches have a vein spine that extends to the posterior oblique in the center of the ventral region. The last caudal vertebrae are tilted backward and upward to form the caudal rod bone.
3. Appendicular skeleton
These include the girdle and fin bones.
(1) Shoulder girdle and pectoral-fin branchiostoma
Shoulder girdle: slightly bowed, connected to the skull, composed of 6 bones.
Spatula: located behind and below the gill cover bone, it is a large, flat and broad bone with the anterior and dorsal segments cocked.
Upper spatula: a rod-shaped bone attached to the dorsal segment of the spatula, the shoulder girdle is connected to the skull through the upper spatula.
Urostylus: Located in front of the ventral part of the spatula, with a foramen in the bone.
Scapula: a small, irregularly triangular bone between the rostrum and the spatula, with a foramen.
Middle rostral bone: 1 small saddle-shaped bone spanning between the scapula and the rostral bone.
Posterior spatula: Located behind and inside the spatula, it is an elongated rod-shaped bone that is slightly "S"-shaped, slightly enlarged and flattened at its dorsal end, and is connected to the spatula.
②Pectoral fin branchiostegal bone
The pectoral fins are composed of four short, flattened fin stretcher bones, which are connected to form a thin sheet of bone that is not healed, the anterior end of which is connected to the rostrum and scapula, and the posterior end is connected to the pectoral fin bar.
(2) Girdle and ventral fin branchials
The girdle consists of 1 pair of unnamed bones, which are forked at the anterior end and the left and right bones are connected in the middle.
The ventral fins have only one pair of small basal fin bones attached to the inner side of the nameless bones. The nameless bones are directly connected to the ventral fin rays.
(3) Odd-fin bones
Of the dorsal and anal fin rays, the first 3 form rigid fin spines, the first 2 spines are short, the first is especially small, and the third is particularly strong, with its posterior margin serrated.
Each fin is supported by 1 fin tambour bone, which expands at its base into a laterally flattened wedge-shaped piece of bone that inserts between the medullary spines of the spine (dorsal fin) or between the vein spines (anal fin).
In the caudal fin, the caudal pole bone and the medullary and vein spines of its first two vertebrae are deformed into a flat, broad bone sheet that serves as a branchial fin bone and directly connects the fins.
Observe a specimen of a shark's skull, which remains cartilaginous throughout its life and consists of two parts, the cranium of the brain and the cranium of the pharynx.
The cerebral cranium is a complete sac of cartilage. Observed from the back of the cranium on each side of the anterior base of the cranium is a hemispherical nasal capsule, behind the nasal capsule on each side of the cranium is a large depression for the orbits, and behind the orbits is a raised portion for the auditory capsule. A larger aperture at the dorsal surface of the base of the muzzle is the chimney, which is covered with a membrane when living. A central hole at the posterior end of the cranium is the foramen magnum occipitalis.
The pharyngeal cranium consists of seven pairs of cartilaginous arches, the first pair being the maxillary arches, the second pair the lingual arches, and the third to seventh pairs the gill arches. The pharyngeal cranium can be viewed from the lateral and ventral surfaces.
Note the way the shark's maxillary arches are attached to the cranium.
II. Assignments
(2) Draw one carapace vertebrae and one caudal vertebrae of the carp (or crucian carp), indicating the name of each part.
2. Reflective questions: Try to summarize the main characteristics of scleractinian fishes and the morphological and structural features of fishes that are adapted to life in water.
3. Quiz questions
(1) What are the parts of the respiratory system of carp (or crucian carp)? How do they accomplish the respiratory process?
(2) What are the similarities and differences between the skulls of carp and shark?