What are Arrow Worms?

The arrowhead is a hairy jaw, and its surface is covered with a layer of epidermis made of cells (the thickening of the epidermis is called the neck). The head has hooks (curved thorns for catching), covered with a hood (or thin leather folds), and the skin folds can be retracted when the arrow worms catch prey. The muscles of the head control the movements of the hooks, teeth, and mouth; the muscles of the body are arranged in rows, with several horizontal bands. The arrowhead swims in the water by contracting the longitudinal muscles and flapping the tail. The nervous system consists of large brain ganglia and sensory nerves (such as the optic nerve and coronary nerves). The brain nerves are connected to the abdominal ganglia by a pair of nerve cords. There are also ganglia and nerves along the trunk. The body surface is interspersed with most tactile receptors and is a small round ciliated protrusion.

Arrowworm is

The arrow body is thin and small, sagittal, divided into three parts: head, trunk and tail. Mid and torso with

Seafood. There are more than 20 species known along the coast of China, and the common one is obese arrowworm. This kind of arrow worms gathers well. Some people have found more than a thousand arrow worms in a cubic meter of seawater.

Arrow worm

Although some species are distributed worldwide, others are distributed only in certain areas of the ocean. Southeast Asia has the most species in the ocean.

Hermaphrodite, usually allogeneic fertilization. A pair of ovaries, arranged along the body cavity wall of the trunk, attached by the mesangium, filled with rows of unfertilized eggs. After mating, sperm are stored in the fertilization sac in the fallopian tube. The testis is located in the body cavity of the tail; a vas deferens connects the testis with the opening in the body wall.

A class of invertebrates of the genus Chaetozoa. The only species that exists today are the Scirpidae, all of which live in the ocean and are one of the important groups of marine zooplankton. There are not many species, but a large number, widely distributed in the world's oceans, and are closely related to the marine environment. Its research history, like other marine plankton, has also developed from marine biology to biological oceanography. However, due to its biological particularity, the study of morphology, classification, and system status has been receiving attention. With the development of biological oceanography, it has been gradually deepened and new discoveries and insights have been made. Natural ecology has always been the mainstream of research. With the infiltration of biochemical and physiological disciplines, it has gradually combined with experimental ecology, and the development of hairy jaw biology and marine ecology has become increasingly close. ^[2] Since Martin Slabber (1768) first discovered the arrow worm in the offshore waters of the Netherlands, a related paper was published from 1769 to 1778, and it has been more than 200 years. He called these animals zee worms or sagitta. Scores-by (1820) also saw arrow worms in whale food. Quoy and Gaimard (1827) reported that arrow worms, known today as Sagitta bipunctata, were collected in the Strait of Gibraltar in 1826. Soon, A. d'Orbigny (1843), during the voyage in South America, five woolly jaw specimens were found. R. After Darwin participated in the British Navy's "Begel" ship's global expedition (1831-1836), in 1844 it was reported that such animals are abundant in the North Atlantic and Brazil, Argentina, and Chile. Since then, hairy jaws have entered the field of marine zooplankton research.