ZOOLOGY: A STUDY GUIDE - Ye. O. Nevedomska - 2013

LECTURE 12. PHYLUM ARTHROPODA

Did you know that...

- When searching for food, crayfish move forward using their four pairs of thoracic walking legs. However, when startled, they swim backward by powerfully flapping their tail fan, which scoops Water underneath the abdomen.

- Freshwater crayfish are capable of regenerating lost limbs. However, this does not happen all at once, but rather gradually: after each molt, when their growth processes are heightened. Adult males take 1.5–2 years to regenerate a lost limb, whereas females, which molt less frequently, require 3–4 years.

- The silk threads of large golden orb-weaver spiders (Nephila) were used by Polynesians to weave fishing nets and sew clothing. In 1903, a sample of spider silk fabric brought from Madagascar was exhibited at the World's Fair in Paris.

- A scout bee that has found a food source communicates its Location to other bees through a dance. It runs across the honeycomb in a figure-eight pattern. Specific elements of its dance convey the distance to the food source and the flight direction relative to the sun's position in the sky. Other bees interpret this message, use the scout's scent to identify the odor of the place she returned from, and set off to find the food.

- Ancient books and documents have preserved accounts of insect trials. A trial against the larvae of May beetles took place in Switzerland in 1479. The beetles were sentenced to anathema. However, the beetles' defense attorney argued at the trial that it was unworthy to subject insects that had accompanied Noah on his ark to anathema. The bishop then declared that the beetles had been sent by God as punishment for the townspeople's sins. And that was how the matter ended.

FROM THE HISTORY of Science

- The prominent native entomologist G. Ya. Bei-Bienko (1903–1971) wrote that if our planet were to suddenly lose its insects, humanity would face a catastrophe: a vast number of animal and plant species would disappear, people would lose many sources of food and other essential products, and soil fertility would decline.

From The history of Discoveries

- Initially, The Study of the insect world was not yet tied to practical demands, although it was spurred by the flourishing of natural science that began in the 17th century. At that time, the Swiss naturalist Charles Bonnet (1720–1793) made a fascinating discovery: aphids crawling on plantain leaves had reproduced for several generations consisting exclusively of females that reproduced without the participation of males. This discovery prompted serious research into an entire group of animals previously overlooked by researchers.

- The distinguished French scientist René Réaumur (whose name later became associated with the thermometer design he proposed) published a six-volume work titled *Memoirs for Serving to the History of Insects*. These substantial volumes were published over the course of 8 years (1734–1742).

- In Germany, within the ancient city of Nuremberg, August Johann Rösel von Rosenhof (1705–1759) published his *Monthly Amusements of Insectology* for a small circle of interested individuals, presented as small, separately issued booklets with elegant artistic designs.

From the World of Science

- Studying insect development from egg to adult form lifted the veil of mystery surrounding the phenomena of the "spontaneous generation" and sudden disappearance of worms that attacked orchards and gardens. Thus, it turned out that these pests were directly related to the insect life cycle, and agricultural specialists learned about The Nature of the enemies of cultivated plants and began implementing measures to combat them.

- Termites cause massive damage by destroying human-built wooden structures, particularly in southern regions. U.S. scientists are thoroughly studying the lifestyle of these insects. During an expedition, researchers from Louisiana observing termite behavior noticed small white balls inside the termite mounds. Analysis revealed that these were naphthalene, a classic anti-moth agent. Their astonishment was boundless, as moths could hardly survive alongside such sharp-toothed insects. Meanwhile, microscopic nematodes and microorganisms likely tormented the fastidious termites, prompting them to use a pesticide to disinfect their nests. However, where these diligent housekeepers "purchase" naphthalene remains a mystery. Scientists suggest that termites extract the substance from the Materials they use to build their nests or from the metabolic products of beneficial symbiotic microorganisms.

- In Diptera, sounds are produced during flight through vibration and serve as a means of communication. For instance, males detect the sound of a female through the vibrations of her wings, which beat at a rate of 350 strokes per second in some species and 500–550 in others. Based on these findings, a method for combating mosquitoes was developed: they are lured to a specific location using a recorded mosquito buzzing sound played on a tape recorder.

- Within 10 minutes, a female bedbug manages to ingest a Blood meal weighing twice its own body weight. Blood-feeding in bedbugs can be viewed as an adaptation for utilizing prey that is vastly larger than themselves. The proboscis of a bedbug creates a puncture in human Skin 500 times smaller than the finest syringe needle.

The Evolutionary Process

- In their structural plan, Arthropods are very similar to Annelids. It is no coincidence that in the 19th century, the zoologist Georges Cuvier united annelids and arthropods into a single taxon "Articulata," meaning "jointed," which points to the evolutionary affinity of these groups.

- Comparative morphological analysis of crustaceans has shown that each modern subclass possesses several unique ancestral traits. For example, in branchiopods (Anostraca), the HEAD is not fused and retains traces of segmentation; Malacostraca possess abdominal appendages (a primitive trait), and some species even have two pairs of Kidneys.

- The most ancient group consists of aquatic chelicerates with branchial Respiration: horseshoe crabs and eurypterids (sea scorpions). Eurypterids were the first to move onto land, as evidenced by fossil transitional forms linking eurypterids to scorpions, which already belong to terrestrial chelicerates.