Argonaut (animal)

Sexual dimorphism is the condition where sexes of the same species exhibit different morphological characteristics, particularly characteristics not directly involved in reproduction. The condition occurs in most animals and some plants. Differences may include secondary sex characteristics, size, weight, color, markings, or behavioral or cognitive traits. Male–male reproductive competition has evolved a diverse array of sexually dimorphic traits. Aggressive utility traits such as “battle” teeth and blunt heads reinforced as battering rams are used as weapons in aggressive interactions between rivals. Passive displays such as ornamental feathering or song-calling have also evolved mainly through sexual selection. These differences may be subtle or exaggerated and may be subjected to sexual selection and natural selection. The opposite of dimorphism is monomorphism, when both biological sexes are phenotypically indistinguishable from each other.

A hectocotylus is one of the arms of male cephalopods that is specialized to store and transfer spermatophores to the female. Structurally, hectocotyli are muscular hydrostats. Depending on the species, the male may use it merely as a conduit to the female, analogously to a penis in other animals, or he may wrench it off and present it to the female.

Sperm is the male reproductive cell, or gamete, in anisogamous forms of sexual reproduction. Animals produce motile sperm with a tail known as a flagellum, which are known as spermatozoa, while some red algae and fungi produce non-motile sperm cells, known as spermatia. Flowering plants contain non-motile sperm inside pollen, while some more basal plants like ferns and some gymnosperms have motile sperm.

Parasitic worms, also known as helminths, are large macroparasites; adults can generally be seen with the naked eye. Many are intestinal worms that are soil-transmitted and infect the gastrointestinal tract. Other parasitic worms such as schistosomes reside in blood vessels.

Calcareous is an adjective meaning "mostly or partly composed of calcium carbonate", in other words, containing lime or being chalky. The term is used in a wide variety of scientific disciplines.

Aragonite is a carbonate mineral, one of the three most common naturally occurring crystal forms of calcium carbonate, CaCO3. It is formed by biological and physical processes, including precipitation from marine and freshwater environments.

Calcite is a carbonate mineral and the most stable polymorph of calcium carbonate (CaCO3). It is a very common mineral, particularly as a component of limestone. Calcite defines hardness 3 on the Mohs scale of mineral hardness, based on scratch hardness comparison. Large calcite crystals are used in optical equipment, and limestone composed mostly of calcite has numerous uses.

Magnesium carbonate, MgCO3, is an inorganic salt that is a colourless or white solid. Several hydrated and basic forms of magnesium carbonate also exist as minerals.

The phragmocone is the chambered portion of the shell of a cephalopod. It is divided by septa into camerae.

A cave or cavern is a natural void in the ground, specifically a space large enough for a human to enter. Caves often form by the weathering of rock and often extend deep underground. The word cave can refer to smaller openings such as sea caves, rock shelters, and grottos, that extend a relatively short distance into the rock and they are called exogene caves. Caves which extend further underground than the opening is wide are called endogene caves.

Venom or zootoxin is a type of toxin produced by an animal that is actively delivered through a wound by means of a bite, sting, or similar action. The toxin is delivered through a specially evolved venom apparatus, such as fangs or a stinger, in a process called envenomation. Venom is often distinguished from poison, which is a toxin that is passively delivered by being ingested, inhaled, or absorbed through the skin, and toxungen, which is actively transferred to the external surface of another animal via a physical delivery mechanism.

The salivary glands in mammals are exocrine glands that produce saliva through a system of ducts. Humans have three paired major salivary glands, as well as hundreds of minor salivary glands. Salivary glands can be classified as serous, mucous, or seromucous (mixed).

Crustaceans form a large, diverse arthropod taxon which includes such animals as decapods, seed shrimp, branchiopods, fish lice, krill, remipedes, isopods, barnacles, copepods, amphipods and mantis shrimp. The crustacean group can be treated as a subphylum under the clade Mandibulata. It is now well accepted that the hexapods emerged deep in the Crustacean group, with the completed group referred to as Pancrustacea. Some crustaceans are more closely related to insects and the other hexapods than they are to certain other crustaceans.

Jellyfish and sea jellies are the informal common names given to the medusa-phase of certain gelatinous members of the subphylum Medusozoa, a major part of the phylum Cnidaria. Jellyfish are mainly free-swimming marine animals with umbrella-shaped bells and trailing tentacles, although a few are anchored to the seabed by stalks rather than being mobile. The bell can pulsate to provide propulsion for highly efficient locomotion. The tentacles are armed with stinging cells and may be used to capture prey and defend against predators. Jellyfish have a complex life cycle; the medusa is normally the sexual phase, which produces planula larvae that disperse widely and enter a sedentary polyp phase before reaching sexual maturity.

A salp or salpa is a barrel-shaped, planktic tunicate. It moves by contracting, thereby pumping water through its gelatinous body, one of the most efficient examples of jet propulsion in the animal kingdom. The salp strains the pumped water through its internal feeding filters, feeding on phytoplankton.

Cephalopod ink is a dark-coloured or luminous ink released into water by most species of cephalopod, usually as an escape mechanism. All cephalopods, with the exception of the Nautilidae and the Cirrina, are able to release ink to confuse predators.

A tuna is a saltwater fish that belongs to the tribe Thunnini, a subgrouping of the Scombridae (mackerel) family. The Thunnini comprise 15 species across five genera, the sizes of which vary greatly, ranging from the bullet tuna up to the Atlantic bluefin tuna, which averages 2 m (6.6 ft) and is believed to live up to 50 years.

The term billfish refers to a group of saltwater predatory fish characterised by prominent pointed bills (rostra), and by their large size; some are longer than 4 m (13 ft). Extant billfish include sailfish and marlin, which make up the family Istiophoridae; and swordfish, sole member of the family Xiphiidae. They are often apex predators which feed on a wide variety of smaller fish, crustaceans and cephalopods. These two families are sometimes classified as belonging to the order Istiophoriformes, a group which originated around 71 million years ago in the Late Cretaceous, with the two families diverging around 15 million years ago in the Late Miocene. However, they are also classified as being closely related to the mackerels and tuna within the suborder Scombroidei of the order Perciformes. However, the 5th edition of the Fishes of the World does recognise the Istiophoriformes as a valid order, albeit including the Sphyraenidae, the barracudas.

A dolphin is an aquatic mammal within the infraorder Cetacea. Dolphin species belong to the families Delphinidae, Platanistidae, Iniidae, Pontoporiidae, and the extinct Lipotidae. There are 40 extant species named as dolphins.

Lancetfishes are large oceanic predatory fishes in the genus Alepisaurus in the monogeneric family Alepisauridae.

The mahi-mahi or common dolphinfish is a surface-dwelling ray-finned fish found in off-shore temperate, tropical, and subtropical waters worldwide. Also widely called dorado and dolphin, it is one of two members of the family Coryphaenidae, the other being the pompano dolphinfish. These fish are most commonly found in the waters around the Gulf of Mexico, Costa Rica, Hawaii and the Indian Ocean.

Argonauta joanneus is an extinct species of octopus assigned to the genus Argonauta. It was described in 1915 based on fossil material from the Middle Miocene of Austria. It was found in fine sandy clay.

Extinction is the termination of a kind of organism or of a group of kinds (taxon), usually a species. The moment of extinction is generally considered to be the death of the last individual of the species, although the capacity to breed and recover may have been lost before this point. Because a species' potential range may be very large, determining this moment is difficult, and is usually done retrospectively. This difficulty leads to phenomena such as Lazarus taxa, where a species presumed extinct abruptly "reappears" after a period of apparent absence.

Argonauta argo, also known as the greater argonaut, is a species of pelagic octopus belonging to the genus Argonauta. The Chinese name for this species translates as "white sea-horse's nest".

Argonauta hians, also known as the winged argonaut, muddy argonaut or brown paper nautilus, is a species of pelagic octopus. The common name comes from the grey to brown coloured shell. The Chinese name for this species translates as "Grey Sea-horse's Nest". The female of the species, like all argonauts, creates a paper-thin eggcase that coils around the octopus much like the way a nautilus lives in its shell. The eggcase is characterised by a wide keel that gives it a square appearance, few rounded tubercles along the keel, and less than 40 smooth ribs across the sides of the shell. The shell is usually approximately 80 mm in length, although it can exceed 120 mm in exceptional specimens; the world record size is 121.5 mm.

The Reverend John Lightfoot was an English parson-naturalist, spending much of his free time as a conchologist and botanist. He was a systematic and effective curator of the private museum of Margaret Bentinck, Duchess of Portland. He is best known for his Flora Scotica which pioneered the scientific study of the plants and fungi of Scotland. He was elected a Fellow of the Royal Society for his scientific work.He was an excellent scholar in many branches of literature; but after the study of his profession, he addicted himself chiefly to that of botany and conchyliologie [sic]. He excelled in both.

Argonauta nouryi, also known as Noury's argonaut, is a species of pelagic octopus. The female of the species, like all argonauts, creates a paper-thin eggcase that coils around the octopus much like the way a nautilus lives in its shell. The shell is usually approximately 80 mm in length, although it can exceed 90 mm in exceptional specimens; the world record size is 95.5 mm.

Louis Augustin Guillaume Bosc was a French botanist, invertebrate zoologist, and entomologist.

The Minoan civilization was a Bronze Age Aegean civilization on the island of Crete and other Aegean Islands, whose earliest beginnings date to c. 3500 BC, with the complex urban civilization beginning around 2000 BC, and then declining from c. 1450 BC until it ended around 1100 BC, during the early Greek Dark Ages, part of a wider bronze age collapse around the Mediterranean. It represents the first advanced civilization in Europe, leaving behind a number of massive building complexes, sophisticated art, and writing systems. Its economy benefited from a network of trade around much of the Mediterranean.

Crete is the largest and most populous of the Greek islands, the 88th largest island in the world and the fifth largest island in the Mediterranean Sea, after Sicily, Sardinia, Cyprus, and Corsica. Crete rests about 160 km (99 mi) south of the Greek mainland, and about 100 km (62 mi) southwest of Anatolia. Crete has an area of 8,450 km2 (3,260 sq mi) and a coastline of 1,046 km (650 mi). It bounds the southern border of the Aegean Sea, with the Sea of Crete to the north and the Libyan Sea to the south.

Mycenaean Greece was the last phase of the Bronze Age in Ancient Greece, spanning the period from approximately 1750 to 1050 BC. It represents the first advanced and distinctively Greek civilization in mainland Greece with its palatial states, urban organization, works of art, and writing system. The Mycenaeans were mainland Greek peoples who were likely stimulated by their contact with insular Minoan Crete and other Mediterranean cultures to develop a more sophisticated sociopolitical culture of their own. The most prominent site was Mycenae, after which the culture of this era is named. Other centers of power that emerged included Pylos, Tiryns, Midea in the Peloponnese, Orchomenos, Thebes, Athens in Central Greece and Iolcos in Thessaly. Mycenaean settlements also appeared in Epirus, Macedonia, on islands in the Aegean Sea, on the south-west coast of Asia Minor, Cyprus, while Mycenaean-influenced settlements appeared in the Levant, and Italy.

A beehive tomb, also known as a tholos tomb, is a burial structure characterized by its false dome created by corbelling, the superposition of successively smaller rings of mudbricks or, more often, stones. The resulting structure resembles a beehive, hence the traditional English name.

Jules Gabriel Verne was a French novelist, poet, and playwright. His collaboration with the publisher Pierre-Jules Hetzel led to the creation of the Voyages extraordinaires, a series of bestselling adventure novels including Journey to the Center of the Earth (1864), Twenty Thousand Leagues Under the Seas (1870), and Around the World in Eighty Days (1872). His novels, always well documented, are generally set in the second half of the 19th century, taking into account the technological advances of the time.

Marianne Craig Moore was an American modernist poet, critic, translator, and editor. Her poetry is noted for formal innovation, precise diction, irony, and wit.

Gift from the Sea is a book by Anne Morrow Lindbergh first published in 1955.

The Swiss Family Robinson is a novel by Johann David Wyss, first published in 1812, about a Swiss family of immigrants whose ship en route to Port Jackson, Australia, goes off course and is shipwrecked in the East Indies. The ship's crew is lost, but the family and several domestic animals survive. They make their way to shore, where they build a settlement, undergoing several adventures before being rescued; some refuse rescue and remain on the island.

Arabidopsis thaliana, the thale cress, mouse-ear cress or arabidopsis, is a small flowering plant from the mustard family (Brassicaceae), native to Eurasia and Africa. Commonly found along the shoulders of roads and in disturbed land, it is generally considered a weed.

The Argonaute protein family, first discovered for its evolutionarily conserved stem cell function, plays a central role in RNA silencing processes as essential components of the RNA-induced silencing complex (RISC). RISC is responsible for the gene silencing phenomenon known as RNA interference (RNAi). Argonaute proteins bind different classes of small non-coding RNAs, including microRNAs (miRNAs), small interfering RNAs (siRNAs) and Piwi-interacting RNAs (piRNAs). Small RNAs guide Argonaute proteins to their specific targets through sequence complementarity, which then leads to mRNA cleavage, translation inhibition, and/or the initiation of mRNA decay.