What are the characteristics of the 79 page squid on the 5th grade winter vacation homework

The body can be divided into three parts: the head, the feet, and the trunk, which corresponds to the visceral mass and is covered by a muscular mantle with a calcareous inner shell. Head.

The anterior end of the body is spherical, with the mouth at its apex, surrounded by oral membranes, and 5 pairs of wrists on the periphery. There are a pair of well-developed eyes on both sides of the head, and the structure is complex. There is an oval-shaped fossa at the lower back of the eye, called the olfactory trap, which is the olfactory organ, and the olfactory apparatus of gastropods is a chemoreceptor.

The foot has been specialized into the wrist and the funnel. There are 10 wrists, symmetrically arranged on the left and right, the first pair of the back is **, and the ventral side is 2-5 pairs, of which the fourth pair of wrists is particularly long, and the end is swollen and tongue-like, called tentacular arm, which can be predated and can shrink into the wrist sac. The inside of each wrist is equipped with 4 rows of suction cups with handles, and the tentacle only has 10 rows of small suction cups on the inside of the terminal tongue, which is called tentacular club.

The middle sucker of the fifth wrist on the left side of the male is degenerated and specialized into a genital carpal or hectocotylized arms. It can transport sperm pods into the female body and play the role of a mating organ. Male and female can be distinguished based on stemmed wrists.

The ventral side of the infundibular head, the base is broad, hidden in the mantle cavity, and there is an oval cartilage depression on each side of the ventral surface called the adhering groove. It coincides with the adhering ridge on the ventral side of the mantle, such as the child-mother buckle, called the adhering apparatus, which can control the opening and closing of the mantle foramen. The front end of the funnel is a simple water pipe, exposed outside the mantle, and there is a tongue flap inside the water pipe to prevent water from flowing backwards.

When the locker is opened, the muscular mantle expands, and seawater flows from the mantle hole into the mantle cavity; The latch is fastened, the mantle hole is closed, the mantle is contracted, and the pressurized water is sprayed out from the water pipe of the funnel. This is the driving force behind the squid's movement. Torso.

It is pouch-shaped, dorsoventrally slightly flattened, and posterior to the head. The outer part is covered by a very muscular mantle, and the inner part is the visceral mass. The torso has fins on both sides, the fins are separated at the end of the torso, and the fins play a balancing role in swimming. Due to the presence of pigment cells under the epithelial side of the dorsal side of the torso, ** can change the shade of color.

The squid's body is positioned according to its living state in the water, with the head end being the front, the trunk ending being the back, the side with the funnel being the abdomen, and the opposite side being the back. However, according to the morphological comparison between the mollusk system and the squid, its front end should be ventral, because the foot is ventral, the back end is the back, the dorsal side is the front, and the ventral side is the back, which is the morphological position of the squid.

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