Definitions

1. Aceria - is a genus of microscopic, plant-feeding mites belonging to the family Eriophyidae, commonly referred to as eriophyid mites.  Aceria mites are notorious for their ability to cause various plant deformities and diseases, including galls, leaf curl, and other abnormal growths in trees like coconut.

2. Acorn worms  - (pronounce A-corn; எ கோன்) belong to class Enteropneusta, they are marine invertebrates belonging to the phylum Hemichordata, closely related to both chordates (which include vertebrates) and echinoderms (like starfish). They are named for the shape of their proboscis (உறிஞ்சுக்குழல்), which resembles an acorn.  Acorn worms play an important role in marine ecosystems, particularly in the recycling of organic material within the seabed. e.g. Enteropneusta, Balanoglossus, Saccoglossus.

3. Ambulacral system - also known as the water vascular system, is a unique and complex hydraulic system found in echinoderms (such as starfish, sea urchins, and sea cucumbers). This system plays a key role in their movement, feeding, respiration, and sensory reception. 

4. Apiculture - is also known as beekeeping, is the practice of managing and maintaining bee colonies, typically honeybees (Apis mellifera), for the purpose of producing honey, beeswax, and other products, as well as providing pollination services to crops 

5. Apolysis - Refers to the process of separation of gravid proglottids (those filled with fertilized eggs) from the strobili (the chain of proglottids) of  tape worm (Taenia sp.) and are passed out of the host's body with feces.

6. Aristotle's lantern - It is a specialized, complex feeding apparatus found in sea urchins (class Echinoidea, phylum Echinodermata). It consists of five calcareous (calcium-based) plates or teeth that are arranged in a pentagonal structure and are used for scraping, cutting, and chewing food, primarily algae, off hard surfaces like rocks.

7. Ascariasis - is a parasitic infection caused by the roundworm Ascaris lumbricoides, one of the most common intestinal parasites in humans. This infection occurs primarily in areas with poor sanitation and hygiene.

8. Autoinfection - refers to a process where an insect becomes reinfected by a pathogen (such as a parasite or a disease-causing organism) that it has already been carrying or that originated from its own body. This phenomenon can have significant implications for insect health, population dynamics, and pest management. E.g. Some bacteria like Wolbachia can induce autoinfection, they are common endosymbionts in many insects, and they can affect host reproduction and lead to persistent infections.

9. Biodiversity (பல்லுயிர்) - is the variety of all living organisms on Earth, including plants, animals, microorganisms, and the ecosystems they form. It encompasses genetic diversity, species diversity, and ecosystem diversity. Biodiversity is essential for maintaining ecological balance, supporting life systems, and providing resources like food, medicine, and clean air. 

10. Bladder worm - it refers to the larval stage of certain parasitic flatworms, specifically those from the genus Echinococcus. Their infection leads to the formation of characteristics hydatid cysts. These organisms are of significant veterinary and medical importance because they can cause serious diseases in both animals and humans. 

11. Carrier host - A carrier host is an organism that harbors a pathogen without showing symptoms of the disease and can transmit the pathogen to other susceptible hosts. The carrier host plays a key role in the life cycle of the pathogen. e.g. Rhodents are carrier of leptospirosis and plague pathogens. 

12. Choanocytes - (pronounce Coano-cytes; கோவநோ சைட்ஸ் ) also known as collar cells, are specialized cells found in sponges (phylum Porifera). These cells play a crucial role in the feeding and water flow systems of sponges, allowing them to filter food particles from water.

13. Cimex - is a genus of insects belonging to the family Cimicidae, commonly known as bed bugs. The most well-known species within this genus is Cimex lectularius.

14. Cnidocytes - (pronounce nido-cytes; நைடோ சைட்ஸ்) also known as cnidoblasts or nematocytes, are specialized cells unique to animals in the phylum Cnidaria (which includes jellyfish, sea anemones, corals, and hydra). In fact the word Cnidaria comes from the Greek word "cnidos," which means "stinging nettle" (கொட்டும் தன்மை உடைய மயிர் இழைகள் கொண்ட).These cells are used primarily for defense and capturing prey.

15. Cold-blooded animals - also known as ectotherms or poikilotherms, rely on external environmental sources to regulate their body temperature. Their body temperature changes with the surrounding environment and have low metabolic rate. They do not generate enough internal heat to maintain a stable temperature. e.g. reptiles, amphibians and fish.

16. Composite fish culture - A type of fish culture where in maximum exploitation of the aquatic resources through the introduction of selected varieties of compatible fish to achieve high productivity is called composite fish culture or polyculture. e.g. growing of grass carp, silver carp, scale carp and mirror carp in the ratio of 5: 3: 8: 2. for maximum productivity. 

17. Conchiolin - is an organic protein substance found in the shells of mollusks and is a key component of the nacre (also known as mother-of-pearl) and the shell structure itself. It binds together calcium carbonate crystals, which make up the hard, mineral part of the shell, providing structure and protection. 

18. Ctenophora - (pronounce teno-phora; டினோ போரா) commonly known as comb jellies, are a phylum of marine invertebrates known for their gelatinous bodies and distinctive rows of cilia (ctenes) used for locomotion. They are an important group in marine ecosystems and are known for their beauty, often displaying bioluminescence in the dark oceans.

19. Cysticercosis - is a parasitic infection caused by the larval stage of the tapeworm Taenia solium, which is commonly known as the pork tapeworm. This condition occurs when a person ingests the eggs of the tapeworm, often through contaminated food or water. The larvae then migrate to various tissues in the body, where they can develop into cysticerci (larval cysts). 

20. Didelphic - refers to an organism having two uteri or two reproductive tracts. e.g. Many species of nematodes have a didelphic reproductive system, meaning they possess two uteri and two oviducts. This feature allows them to produce a large number of eggs.

21. Digenetic parasites - are organisms that require two different hosts to complete their life cycle, typically involving a sexual stage in one host and an asexual stage in another. The term "digenetic" literally means "two generations" or "two hosts." A classic example of a digenetic parasite is Plasmodium, the causative agent of malaria, which undergoes part of its life cycle in humans (asexual reproduction) and part in mosquitoes (sexual reproduction).

22. Dioecious animals - are species in which individuals are distinctly male or female, meaning each individual organism has only one type of reproductive organ. In other words, there are separate sexes, with males producing sperm and females producing eggs. e.g. round worms.

23. Endophagic vector - refers to a type of vector (typically an insect or arthropod) that not only transmits a pathogen but also serves as a host for the pathogen during its development. In this context, "endophagic" indicates that the vector feeds on the interior tissues of a host organism or penetrating into the host body.

24. Eusocial insects - Eusocial insects are highly social species that exhibit the most complex form of social organization in the animal kingdom. e.g. ants, bees and termites.

25. Formicary - is the term used for an ant nest. It refers to the underground or above-ground structure often composed of interconnected chambers and tunnels, where ants live, work, and rear their young. 

26. Gravid proglottids - They are the mature, egg-filled segments of adult tapeworms. Tapeworms, which are segmented flatworms, consist of a head (scolex) and a series of repeating body segments called proglottids, each containing reproductive organs.  As the tapeworm matures, the proglottids closer to the tail end become gravid, meaning they are filled with thousands of eggs. Thus gravid proglottids play a critical role in dispersing eggs into the environment.

27. Gastropoda - is the largest and most diverse class within the phylum Mollusca, which includes organisms such as snails, slugs, limpets, and sea hares. They have unique features such as torsion, a 180-degree twisting of the body that occurs during development, they have coiled shells protecting against predators and harsh environments; and muscular foot for locomotion. Gastropods can be found in a wide range of environments, including marine, freshwater, and terrestrial habitats. 

28. Haltere - refers to a modified hindwing structure found in certain insects, particularly in the order Diptera (flies). They help in maintaining balance and stability, they possess sensory receptors that detect changes in the movement and orientation. 

29. Hatching happas - they are enclosures made of fine mesh or cloth that are used in fish farming, particularly in aquaculture, for the controlled breeding and hatching of fish eggs. These structures are typically submerged in a water body (like ponds or tanks) to provide a safe environment for the eggs to hatch and protect the larvae from predators, unfavorable conditions, or contamination. 

30. Helminth - a general term refers to parasitic worms, it includes Platyhelminthes or flatworms (flukes and tapeworms) and the Nematoda or roundworms. 

31. Hermophrodites (இருபாலுயிரி) - Sexes are not separate, i.e., eggs and sperm are produced by the same individual. e.g. sponges.

32. Hydatid cyst - A hydatid cyst is a fluid-filled cystic structure formed in tissues as part of the life cycle of the parasitic tapeworm Echinococcus. These cysts develop in intermediate hosts, like sheep or humans, after ingesting eggs of the parasite. It usually spread through contaminated food, water, or direct contact with infected animals. 

33. Hyperinfection - refers to an intensified or overwhelming infection, often involving an increased burden of parasites or pathogens within a host, leading to severe clinical manifestations. This phenomenon is typically seen in cases where the host's immune system is compromised. e.g. Cryptosporidium, a protozoan parasite hyperinfecting on immunocompromised (நோயெதிர்ப்பு குறைபாடு) individuals like AIDS patients. 

34. Hypophysation - is a technique used in aquaculture, particularly in the breeding of fish and other aquatic organisms. This method involves the artificial stimulation of spawning in fish through the administration of hormones, specifically those derived from the pituitary gland (hypophysis). 

35. Insecticide resistance - refers to the ability of insects to withstand exposure to chemicals designed to kill them, making pest control efforts less effective. This phenomenon poses a significant challenge in agriculture, public health, and pest management, leading to increased costs and the need for alternative control methods. 

36. Insect parasitoids - They are a specific type of organism that develop in or on a host insect, ultimately leading to the host's death. Unlike predators, which kill their prey immediately, parasitoids usually do not kill their host until they have completed their development. This unique life cycle has important implications for ecology and pest management. e.g. Braconid wasps on caterpillars and aphids; Trichogramma wasps parasitizing lipidopteran eggs.

37. Key pests - They are specific organisms, often insects or diseases, that cause significant economic damage or yield loss to crops and livestock. Understanding key pests is essential for effective pest management strategies in agriculture and horticulture. e.g. aphids feeding on plant sap and cause stunted growth, Cotton boll worm attack leading to reduced fiber quality and yield.

38. Lac- It is  a resinous secretion  of the insect, Laccifer lacca,  which  is a species of scale  insect. The female  insect deposits lac  on the twigs and  young branches  of several  varieties of soapberry and acacia trees and particularly on  the sacred fig,  Ficus religiosa. The twigs are cut and the  lac  is  melted  off, refined, and used in shellac and varnishes.

39. Mariculture - is a specialized branch of aquaculture that involves the cultivation of marine organisms in the ocean or in specialized facilities like tanks, ponds, or enclosures in coastal waters. It focuses on farming saltwater species such as fish, shellfish, seaweed, and other marine organisms for food, industrial products, and environmental restoration efforts. 

40. Metagenesis - refers to a type of life cycle that involves the alternation between two distinct forms: asexual and sexual reproduction stages, often involving different generations (Alternation of generation). In this cycle, one generation reproduces sexually and the next generation reproduces asexually. e.g. common in cnidarians, such as jellyfish, and certain algae and plants.

41. Metamerism - also refers to the segmentation of an organism's body into repeating units or segments. Many animals have bodies organized in a series of repetitive segments, especially in annelids (earthworm) and arthropods (insects).

42. Metamorphosis - refers to the biological process by which an organism undergoes significant changes in its form and structure from one stage of life to another. Three stages of metamorphosis are Larva, Pupa, Adult. These stages are primarily associated with insects like butterflies, beetles, and flies.

43. Merozoites - are the larval stage of Plasmodium, the malarial parasite, found in the human bloodstream after the liver-stage of the parasite has been completed, the reproduce asexually leading to production of trophozoites.

44. Miracidium larva - is the free-swimming larval stage in the life cycle of digenetic trematodes, such as Fasciola (liver fluke). It hatches from the egg in water and is responsible for infecting the intermediate host, typically a freshwater snail. The miracidium plays a crucial role in transferring the parasite from the environment to the next stage in its development.

45. Moriculture - is the practice of cultivating mulberry trees (genus Morus) primarily for the purpose of silkworm rearing in sericulture. It plays a critical role in the silk production industry, as mulberry leaves are the primary food source for silkworms (Bombyx mori), which produce silk fibers 

46. Notochord (முதுகுத்தண்டு) - is a mesodermally derived rod-like structure formed on the dorsal side during embryonic development in some animals.

47. Obligatory parasite  - They are also known as obligate parasites or organisms that cannot complete their life cycle without exploiting a host. They rely on the host for essential resources such as nutrition, reproduction, or habitat, and cannot survive, grow, or reproduce outside the host environment. e.g. Plasmodium falciparum requires both mosquito and human host to complete their life cycle.

48. Occasional pests - They are insects and other organisms that do not consistently threaten crops or structures but can cause problems when conditions are favorable for their population growth. These pests tend to appear sporadically, often in specific seasons or under certain environmental conditions. e.g. Cabbage loopers on Brassica crops; leafhoppers on alfalfa and soybeans.

49. Oceanodromous migration - refers to the movement of fish or other marine animals entirely within the ocean. Often traveling vast distances for feeding, spawning (முட்டையிடும்), or other life-cycle processes. e.g. Herring, Tuna. These migrations are driven by various factors, such as breeding, feeding, and seasonal changes. 

50. Oncosphere - An onchosphere is the larval stage of certain parasitic tapeworms, the larva contains six tiny hooks (hence also called a hexacanth embryo) that aid in tissue penetration. Its critical for tapworm life cycle and transmission. This stage develops within the eggs of the tapeworm and is an infective form that, once ingested by an intermediate host (e.g. cattle, pig, and fish) it can penetrate the gut wall and enter the tissues. There, it transforms into the next larval stage (cysticerci or hydatid cyst).  

51. Parasitoid - Refers to an organism that lives in close association with a host organism, typically leading to the death of the host. Parasitoids lay their eggs in or on a host, and the larvae develop by feeding on the host’s tissues. e.g. Trichogramma parasitize eggs of butterfly

52. Pasturage - refers to the vegetation and floral resources available in the environment from which bees collect nectar and pollen.The quality and diversity of pasturage impact the flavor, color, and quality of honey produced. Different plants, like clover, wildflowers, or citrus, yield distinct honey types. Pasturage availability also influences bee health, as diverse flora provides a balanced diet, including proteins from pollen and carbohydrates from nectar. 

53. Pebrine disease - is a serious disease affecting silkworms, particularly the Bombyx mori species, which is widely used in the silk industry. The disease is caused by a unicellular, spore forming, microsporidian fungal parasite called Nosema bombycis. Pebrine disease is highly contagious and can cause significant losses in silk production by affecting the health and productivity of silkworms. 

54. Pest resurgence (புத்தெழுச்சி; புத்துயிர்ப்பு) - refers to the phenomenon where pest populations increase significantly after being reduced or controlled through various methods, such as chemical pesticides, biological control, or cultural practices. This resurgence can lead to unexpected pest outbreaks, often resulting in greater pest problems than initially experienced. 

55. Pisciculture - also known as fish farming, is the practice of breeding, rearing, and harvesting fish in controlled environments for commercial purposes. It is a branch of aquaculture focused specifically on the cultivation of fish species, and it plays a vital role in meeting global demand for fish as a food source.

56. Placenta (நஞ்சுக்கொடி) - கருவின் உயிருக்கு ஆதரவாக கருப்பையின் சிறப்பு உறுப்பு. The placenta is a vital organ that develops in the uterus during pregnancy in most mammals, including humans. It serves as the interface between the mother and the developing fetus, facilitating the exchange of nutrients, gases, and waste products. The placenta plays a crucial role in maintaining the health and development of the fetus throughout gestation (கர்ப்பகாலம்).

57. Plasmodium - is a genus of parasitic protozoa that causes malaria in humans and other animals. It is transmitted through the bite of infected female Anopheles mosquitoes. The most dangerous species, Plasmodium falciparum, can cause severe and life-threatening malaria. 

58. Pollination - is the process by which pollen is transferred from the male part (anther) of a flower to the female part (stigma), enabling fertilization. It can occur through wind, water, or animals like bees, birds, and butterflies. Pollination is essential for the production of fruits and seeds in flowering plants. 

59. Propolis (தேனீ பசை) - This is a glue-like substance collected by bees from trees. The sticky resin is mixed with wax to make it into sticky glue which is used to construct the foundation of the comb strong. The bees also use propolis to seal cracks in their hive. 

60. Reservoir host - is an organism that harbors a pathogen or parasite and serves as a long-term host for that organism, allowing it to survive and reproduce without causing significant harm to the host. Reservoir hosts play a crucial role in the ecology of diseases by maintaining the pathogen in the environment and facilitating its transmission to other susceptible hosts, including humans or livestock.  e.g. Bats are known reservoirs for several viruses, including rabies and coronaviruses.; Rodents can act as reservoirs for pathogens like hantavirus and leptospirosis (எலிக்காய்ச்சல்). 

61. Royal Jelly - It is  a milky substance that is made of digested pollens and honey mixed with the secretion of pharyngeal gland of nursing bee. It is loaded with proteins, fats and all of the B vitamins. 

62. Round dance - A kind of dance, performed in circular pattern is a form of communication used by honeybees to convey the location of food sources to their hive mates.  It was discovered by Karl von Frisch, an Austrian ethologist and Nobel Prize laureate. It is one of the two primary dances used by foraging (உணவு தேடுதல்) bees, the round dance specifically communicates that a food source (such as nectar or pollen) is near the hive—usually within 50 to 100 meters, the other being the waggle dance, communicates food sources at long distances > 100 m. 

63. Schizonts - are a stage in the life cycle of certain parasitic protozoa, particularly in the genus Plasmodium, which causes malaria in humans. The schizont stage is part of the asexual reproduction process known as schizogony, where the parasite undergoes multiple rounds of nuclear division before breaking apart into smaller daughter cells called merozoites. 

64. Sericulture, also known as silk farming, is the cultivation of silkworms to produce silk. It is one of the oldest industries in human history, dating back thousands of years, particularly in China. Silk production involves raising silkworms (primarily Bombyx mori) on mulberry leaves, and harvesting the silk they produce to spin into thread. 

65. Spat - It refers to the juvenile stage of oysters, clams, or other bivalve mollusks after they have settled from their larval stage and attached themselves to a surface. This is a crucial stage in pearl farming. 

66. Sporozoites - are the larval stage of Plasmodium, the malarial parasite found in the salivary glands of infected mosquitoes. On biting of mosquitoes on a human, they reach blood stream and later develop into liver-stage parasites (schizonts). 

67. Stomochord - It is a tubular structure found in the hemichordates, specifically in a group called enteropneusts (acorn worms). It projects forward from the roof of the buccal cavity (mouth cavity) into the proboscis. It is not homologuous to notochord and its endodermal in origin.

68. Supersedure - is a natural phenomenon in honeybee colonies where in the workers replace an old, failing, or unproductive queen with a new one. It occurs without the colony swarming and is a key mechanism for ensuring the health and productivity of the hive. During supersedure, the workers rear one or more new queens while the old queen is still alive, and once the new queen emerges and mates, she will take over as the primary egg-laying queen, while the old queen is either killed or allowed to remain for a period.

69. Termitarium (plural: termitaria) - is the habitat or nest built by termites. These nests can be large, complex highly structured and durable, offering protection and regulation of environmental conditions for the termite colony. 

70. Thermoception - is the sensory ability to detect temperature changes, specifically heat and cold, in the environment or within the body allowing organisms to sense temperature variations that are important for survival, such as detecting dangerous heat or cold that could damage tissues. E.g. Snakes like pit viper.

71. Tunicates - also known as sea squirts, marine invertebrates belongs to sub phylum Urochordata are also called tunicates, owing to the unique outer covering they possess, known as a tunic. The tunic is a thick, protective layer that surrounds their bodies, providing both support and defense. While tunicates are chordates, they are quite different from vertebrates, and their adult form can be so simplified that they often don’t appear to share typical chordate characteristics. They are important for understanding the evolution of chordates. 

72. Trophozoites - Trophozoites are the active, feeding, and motile stage of certain protozoan parasites. They are commonly found in organisms like amoebae, flagellates, and ciliates during their life cycle. In this stage, the trophozoite is metabolically active, absorbs nutrients, and can multiply by binary fission. 

In protozoan parasites like Entamoeba histolytica (which causes amoebic dysentery) or Plasmodium spp. (responsible for malaria), trophozoites are critical for the infection process. The trophozoite form typically resides in the host's tissues or body fluids, including the intestinal lumen, blood, or other areas, depending on the specific organism.

73. Warm-blooded animals - also known as endotherms or homeotherms, can generate and regulate their own body heat through internal physiological processes. Their body temperature remains relatively constant, regardless of the surrounding environment and have high metabolic rate, a stable internal body temperature within a narrow range 37oC is maintained. e.g. Mammals and birds.

74. Zoogeography - is the branch of biogeography (உயிர் புவியியல்) that studies the geographic distribution of animal species across the Earth. It examines how and why different species are found in specific regions, considering factors like evolution, migration, climate, and geography.

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