What are some questions about animals

>Breasts are a feature of mammals, generally grow in pairs, symmetrical on both sides, humans and apes have only one pair of breasts, while other rodents have 6-12 pairs of breasts, which is closely related to the birth of many children at a time and a single child. Humans, both male and female, especially Asians, may have additional single or multiple breasts or nipples along the service line from the axilla to the groin, as in lower mammals, in addition to the normal pair of breasts on the chest, which is clinically known as paramastia. It is more common in women, with an incidence of 1%-3%, and generally occurs more frequently in the axilla and anterior chest wall. Some of these secondary breasts only have glands without nipples and areolas, some have nipples, areolas and fat without glands, and can be palpated as soft or moderately tough lumps, the size of the middle walnut or egg.

Fish Characteristics

Marine biologists have been studying fish patterns for several years. They have found that based on the whorls of a fish's scales, they can get a rough idea of that fish's life history, including where it spawned, where it grew, and so on. At first, people used microscopes to compare and categorize fish patterns with little success. A biological company in Seattle, USA, used computers to carry out the analysis, making the whole work much simpler. Analyzing fish patterns is somewhat similar to observing the annual rings of trees. Fish patterns grow about 10 to 13 turns per year. Measuring the spacing, shape, and width of the lines not only tells you the age of the fish, but also how the fish lives. If the stripes are very narrow, it means that the fish is living in a cold area or in an environment where there is a lack of food during this period of time. In summer, when food is abundant, the fish stripe will be especially wide and the gap becomes bigger. Salmon spend their juvenile years in freshwater, and the stripe is much narrower during this time than it would be in the ocean where food is plentiful. For example, there is a species of Pacific sockeye salmon, and by analyzing the fish prints, it was discovered that they spent their early years in the Skinner River Basin in Canada. In this way, one finds the whereabouts of the Pacific sockeye salmon.

Characteristics of birds

An order of the subphylum Vertebrata. The body is feathered, thermostable, oviparous, with an amniotic membrane outside the embryo. Forelimbs into wings, sometimes degenerate. Flying life. The heart is 2 auricles and 2 ventricles. The bones are hollow and filled with gas. In addition to the lungs, the respiratory organs have air sacs to assist respiration. 9021 species have been found in the world; 1186 species in the People's Republic of China.

Structure and function Birds are evolved from the ancient reptiles in the crocodilians, on the one hand inherited some of the structures of reptiles, on the one hand, and on the other hand, appeared adapted to fly and constant temperature of the new structure.

Feathers and Flight The forelimbs of birds are covered with primary and secondary flight feathers and coverts, which become the building blocks of flight, and tail feathers that provide orientation and balance in flight.

Modern birds are toothless, with a degenerated tailbone and no bladder to reduce weight; the bone cavities are inflated, and the skull, lower vertebrae, and pelvis are healed, making the bird solid and lightweight for more efficient flight.

Tarsal bones heal with tibia and metatarsal bones to form tarsal tibia and tarsal metatarsal bones, respectively, and the heel is off the ground to increase flexibility during takeoff and landing. Most birds 4 toes. The toes are backward, which facilitates gripping branches. Due to the special structure of the toe flexor tendons, the toes do not come loose while perching. The bird's feeding, feather grooming, nesting, and defense activities are performed by the beak, resulting in a long neck with multiple connected saddle-shaped neck bones and extremely flexible movement.

Metabolism and temperature Strenuous flight requires a vigorous metabolism. A high body temperature (40±2°C) ensures a high metabolic rate and extends the bird's range of motion both vertically and horizontally. The still air under the cover of feathers forms a good insulating layer, and the rapid cool air currents during flight help to dissipate heat, and the rapid exhalation of water by the birds carries away a great deal of body heat.

Birds have a strong respiratory function, with air passing through the air sacs to a network of capillary bronchial tubes where gases are exchanged and then expelled by the anterior air sacs. Whether inhaling or exhaling, the gas flows in one direction (i.e., double breathing). In addition, airflow in the capillary bronchioles is in the opposite direction of blood flow in the pulmonary capillaries, exchanging oxygen far more efficiently than in mammals. Birds are fully bicirculatory, but the right body artery is preserved. Birds have large heart volumes, fast heartbeats, high blood pressure, and rapid circulation.

Birds ingest food primarily by means of a horny beak and a flexible tongue. In some birds (such as fish-eating birds), the lower end of the esophagus is enlarged and becomes a crop that stores and softens food, but crushing of food is done mainly by a well-developed muscular stomach. The muscular stomach often contains grit to aid in grinding. Birds have strong digestive power and rapid digestion. Due to the reabsorption of water by the renal tubes and cloaca, the bird loses very little water. Seabirds have salt glands in the supraorbital region that secrete hypertonic saline, thus keeping the osmotic pressure of body fluids stable.

Vision and instincts Birds have a well-developed nervous system. Most birds are diurnal. Due to acute vision and color vision, targets on the ground can be detected while flying at high altitudes. The intraocular muscles of birds are transverse muscles, which are responsive and can change the convexity of the cornea and crystal at the same time (double regulation). The eyelids and transient membranes protect the eye from air currents and dust, and the scleral bone ensures that the eye is not deformed by air pressure. A few nocturnal birds have a well-developed sense of hearing, and only the vulture has a relatively well-developed sense of smell.

Egg-laying and brooding Complex structures require long developmental stages; however, flight requires lightness, a contradiction that is resolved by multiple yolks and long incubation times. The right and left sciatic and pubic bones of the bird are not united ventrally, and the open pelvis favors the production of large, hard-shelled eggs.

Behavior and Ecology Birds have many special adaptations to live in a wide variety of environments.

Feeding Birds can be categorized as carnivorous, piscivorous, insectivorous, and phytophagous, as well as many resident and omnivorous types. The diet of some species varies according to seasonal changes, availability of food, habitat characteristics, and other conditions.

Breeding Birds are sexually mature for one to five years. Many birds are hermaphroditic by the time they reach sexual maturity. Most species pair up during breeding. Some species pair up for many years. Some species have more females than males. A few species have multiple males and females. Birds living in pairs of male and female **** the same brood, a male and female birds mostly by the female brood, a female and male birds by the male brood.

Birds in the early stages of reproduction have rutting activities, male and female encounter, the male (a few for the female) to show special posture and song. In some species, especially those with multiple females, fighting often occurs between males. Occupation of the nesting area begins at the end of the rut or at the end of the rut.

The nest is large? (12) the base of the witch as well as the mountain mount footholds on the shoulders of the twilight barrels of the warehouse λ?group Yi ash to restore the D emaciated hublot warehouse λ?Xing aluminum chip father of the Falcon noisy stopping the child comparable to the warehouse fan operculum box insect coriander disaster small "micro warehouse fan visit? Taking risks", "Taking risks", "Taking risks", "Taking risks", "Taking risks" and "Taking risks". Take risks," "Take risks," "Take risks," "Take risks," "Take risks," "Take risks," "Take risks," "Take risks," "Take risks," "Take risks," "Take risks," "Take risks," "Take risks," "Take risks," "Take risks," and so on. What's the best way to do this? What's the best way to get the most out of your life? Carry on with the drought drought? What are you looking for? What is the best way to teach the materials? What's in it for you? The following is a list of the materials used in the treatment of drought. Sewing shoulder gray to restore the 7 callus dumb bragging words troubled? 2 to 13 days (such as small birds) to 21 to 28 days (pheasants, ducks), but some large raptors incubation period of up to 2 months. There are early fledglings, late fledglings, and resident types. Most birds change their plumage once a year, but there are also those that change their plumage twice a year, or even as many as four times (e.g., thunderbirds).

Migration Birds change their habitat in different seasons, either moving from their nesting grounds to their wintering grounds, or returning to their nesting grounds from their wintering grounds, a seasonal phenomenon known as migration. Birds can be categorized into resident birds, summer migratory birds, winter migratory birds, travelling birds, lost birds and so on due to their different migratory habits. Bird migration usually takes place in spring and fall. Fall migration is slow as they leave their nesting areas; spring migration is faster as they are eager to breed.

Classification and Distribution There are two subclasses under the Ornithischia: Archaeopteryx and Archaeopteryx. Under the subclass of present-day birds, there are four general orders: Dentomaxillaria, Palaeomaxillaria, Cuneiformes, and Presentomaxillaria (also known as Succulentes). The People's Republic of China produces only species in the order Imaginata. There are 23 orders under the order Imaginata, of which all have been found in the territory of the People's Republic of China, with the exception of the Cavity Birds and the Mouse Birds. Based on the possible affinities of the respective birds, preliminary inferences can be made about the evolutionary system.

The evolution of birds in the vertebrates of the bird class fossils are relatively rare, has found nearly 1000 extinct species and about 1000 species of fossilized living birds.

Birds of the Jurassic Birds date back to the Late Jurassic (about 140 million years ago). The Archaeopteryx is the only bird found in the Jurassic. From the specimens that have been found, it can be clearly seen that the Archaeopteryx has feathers; the hind foot is opposite to the toe type; the carpometacarpal and tarsometatarsal bones are healed; the structure of the pelvic disk, the clavicle, the beak, the way of jaw joints, and the eyes, and many other features similar to those of the birds. The Patriarchs have alveolar teeth and a long tail with caudal vertebrae; biconcave vertebrae; forewing metacarpal phalanges are free and clawed; and features such as the brain, sternum, ribs, and hind limbs are again close to those of reptiles. Therefore, the originator bird is considered to be an intermediate link between reptiles and birds.

Birds of the Cretaceous Period All birds except the Archaeopteryx belong to the Neornithidae, whose body structure is closer to that of present-day birds. Some of the Cretaceous birds with grooved teeth in their mouths formed the Dentomaxillar Superorder, which includes the Dusky Birds and the Fish Birds. None of the remaining members of the Neornithidae suborder possessed true teeth in their mouths. Appearing from the Cretaceous, they began to flourish in the Eocene, ****34 orders. In recent years some extinct fossils of non-dentate birds have been found in Cretaceous strata, but they are mostly fragmentary. There are four orders of these new jawed birds. Nearly chicken bird order was found in the Late Cretaceous strata in Alberta, Canada, and was named Nearly Chicken Bird in 1940, and a second species was reported in 1971, which is more closely related to Chicken and Goose. The Gobi Birds were found in the Late Cretaceous strata of the Gobi Province of Mongolia, and were named Gobi Birds in 1974, which were presumed to be the early representatives of the flat-breasted birds. 1981 saw the establishment of the genus Antibird based on the fossils of some birds collected from the Late Cretaceous strata of South America, and it was thought that it should be in the middle of the subclasses of the Dentate-maxillar Superorder and the Archaeorhynchus in terms of its evolution and classification, so the Antibirds were established. 1982 saw the discovery of another new Early Cretaceous bird fossil, the Pangaea Bird in Mongolia. In 1982, a new Early Cretaceous bird fossil was found in Mongolia, the Pond Bird, and a new Pond Bird Order was established, pointing out that it might be the earliest synapsid bird and closer to the Owl Order. 1984, bird fossils were found in the Early Cretaceous strata near the city of Yumen in Gansu Province, People's Republic of China*** and the State of China***. The fossilized bird was found in the Early Cretaceous strata near Yumen City, Gansu Province, People's Republic of China. (Related to the fossilized bird of pre-Cretaceous strata of Yumen City, Gansu Province, China) The fossilized bird was found in the Early Cretaceous strata near Yumen City, Yumen Province, China. The fossils were found in the Cretaceous strata. The fossilized wine containers? What is it? Bragging rights? What are you doing? Rustic? The travelers are 2(4)-students. The company's business is to provide a wide range of products and services to the public. Rustic Contempt Nao Sheung take 6? dropsy a form of the order is closer.

Cenozoic birds Early Tertiary fossil record is less, the Eocene and Oligocene protruding thoracic class has a greater development, flat-breasted birds only ostrich order and rumbler order began to appear, has been found nearly 40 extinct family fossils. The Quaternary was a period of great prosperity for birds. Most extant species originate from this period. Flat-breasted species were distributed in the southern hemisphere, but representatives of the rumblers and ostriches were seen in the Middle East and Europe during the Eocene. Fossils of extant ostrich genera have been found in the Miocene of Moldavia and extensively in the Pliocene and Pleistocene of China, Mongolia, Europe and Africa. Fossils of the extant species are found in the Pleistocene of Mongolia, Arabia and Algeria.

There are also some birds with bony projections on their jaws in the Neomandibular birds, which are osteodont birds found in the Eocene-Pliocene, and which have all become extinct. Representatives of the suborder Osteodontiformes? s representatives all have dentary projections, but not grooved teeth. There are nearly 10 genera, distributed throughout Europe, Asia, the Americas, and West Africa.

Theory of the origin of birds There is some agreement that birds originated in the Pseudocrocodile suborder of the Reptilia Choristodontia. Pike's crocodile is a small pseudocrocodile found in the Lower Triassic of South Africa, with a body length of about 1 meter and a long tail. Its skeleton is hollow and its hind limbs are slightly longer than its forelimbs. They may have evolved from an arboreal life, like flying lizards or flying squirrels, jumping between branches and forks (as evidenced by sharp claws, detached fingers, and reversed toes) to flying; or they may have evolved from running on the ground bipedally to birds, like some birds. There is also the view that the direct ancestor of birds was a small dinosaur (Ostrom, 1967), which is thought to have evolved from pseudocrocodilians to the dino-saurids, and then further to the new birds by evolution to the primates.

Based on the differences in the landscape and the breeding range of birds, the territory of the People's Republic of China*** and the country can be divided into seven zones. Among them, the districts of Northeast, North China, Mongolia and New Zealand, and Qinghai and Tibet belong to the Palaearctic boundary, while the districts of Southwest, Central and South China belong to the Eastern Oceanic boundary. The People's Republic of China is the only country in the world that combines two different animal geographic boundaries of considerable size.

Economic significance ①Direct utilization. Includes food (meat, eggs, nests), for stuffing material (down), fertilizer (guano), service (communication pigeons), medicinal (vaccine making), decoration and ornamental use. ② Indirect benefits. Birds can control or destroy various pests and rats, and can protect forests and crops. Some birds (e.g., many buntings) swallow weed seeds, which can be quite beneficial to agriculture. Some birds (e.g., flowerpeckers, sunbirds, etc.) spread pollen, which facilitates plant fruiting. Buzzards and dodos, which are addicted to animal carcasses and filth, and raptors, which destroy sick and weak wild birds and animals, are beneficial to environmental health.

Human beings should protect and attract the beneficial birds, and should rationally utilize the birds with various purposes, and should focus on protecting the precious and rare, especially the endangered species, and prohibit hunting. The People's Republic of China has set up nature reserves in various places, which is an important measure to protect rare and beneficial birds.

Characteristics of Insectivora

(1) The body segments are assembled to form the head, thorax, and abdomen respectively, but not divided

(2) The head is the center of sensation and feeding, with the mouthparts (beak) and 1 pair of antennae, and usually compound eyes and a single eye;

(3) The thorax is the center of locomotion, with 3 pairs of legs, and usually 2 pairs of wings;

(4) The abdomen is the center of reproduction and metabolism, which contains the genitals and most of the internal organs;

(5) Insects undergo a series of internal and external morphological changes during growth and development before they can transform into adults. This change in body form is called metamorphosis.

(6) Insects that chirp are males and females do not chirp

Characteristics of Reptiles

Reptiles have inner and middle ears, lay amniotic eggs, have a neck, have two atria and one ventricle, and the ventricles are incompletely septated.

The characteristics of the two ?2 animals

Amphibians are animals between fish and reptiles, with a twofold life, its characteristics:

First, the skin is thin and moist. It consists of epidermis and dermis containing most of the glands, and many blood vessels are densely packed under the skin;

Secondly, the lungs of amphibians are in the form of sacs, which are separated into tiny terminal air chambers. In addition, the amphibian heart is divided into two auricles and one ventricle. The blood circulation is divided into major and minor circulations.

Characteristics of Mollusks

The phylum Mollusca is second only to the phylum Arthropoda in the number and variety of invertebrates. Most are marine, and a few live on land and in fresh water. The familiar snails, mussels and squid are their representatives.

The morphology of various types of mollusks varies greatly, but some of their main features are still quite similar. For example, the body is soft, not divided into segments (veneers can be divided into segments), can be divided into head, feet, visceral mass, and the back of the skin expansion of the coat membrane (mantle) four parts. Mollusks are dioecious, and a few are hermaphroditic. Most of them are of the marine type, and develop mostly through the planktonic tambourine larvae and facultative plate larvae periods.

The shells secreted by the outer coat gland cells, commonly known as shells, or simply shells. Shells are mostly calcareous shells, with a few having an inner shell, or no shell. Mollusks vary greatly in size, the smallest is less than 1mm, the large ones such as Architeuthis (King Quarry) carapace and the wrist next to the mouth together with a length of more than 36m, is the largest living invertebrates. Mollusks range in geologic age from the Cambrian to modern times.

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Other 2 Answers

Reporting | 2007-12-09 18:19MuXue JieDaMingDingChenYiSe | Grade 4

1.Coat Constant Temperature Lactation

2. Worms:

(1) The body segments are assembled separately to form the head, thorax, and abdomen, but are not divided

(2) The head is the center of sensation and feeding, with a mouthparts (beak) and 1 pair of antennae, and usually compound and single eyes;

(3) The thorax is the locomotor center, with 3 pairs of legs and usually 2 pairs of wings;

(4) The abdomen is the center of reproduction and metabolism, which contains the genitals and most of the internal organs;

(5) Insects undergo a series of internal and external morphological changes during growth and development before they are transformed into adults. This change in body form is called metamorphosis.

(6) Insects that chirp are males, and females do not chirp

The basic characteristics of insects can be summarized as "three segments of the carapace head, thorax, and abdomen, two pairs of wings and six legs; one pair of antennae are borne on the head, and the skeleton is encased in the exterior of the body; the shape of the life is much varied, and the family of the WANGs is found throughout the world."

Fish:Main features of the class Ichthyoplasmata

Fish live all their lives in salt or fresh water and most have a body shape and fins suitable for swimming. They breathe through gills and hunt with upper and lower jaws. The beating heart is divided into an atrium and a ventricle. Blood circulation is unicirculatory. The emergence of the spine and the head led to the development and evolution of the order Ichthyophagy into the group of vertebrates best adapted to life in water. This is due to the fact that there are depths and depths of water and differences in the pressure exerted at each location, from 1 atmosphere at sea level to up to 1,000 atmospheres in deeper areas. The salt content of fresh and salt water ranges from 0.001 to 7% from fresh water to brackish water. In addition, with the different geographical environment, the water temperature difference and oxygen content of the difference is also very large. Because of the diversity of these waters, water layers, water quality and biological and non-biological factors in the water and other aquatic environments, so the body structure of the fish to adapt to different changes in the outside world to produce different changes. Higher than the round mouth class.

Main features of Ichthyoplankton:

-Shape

-Movement

-Skin and Derivatives

-Skeleton

-Digestion

-Respiration

-Circulation Blood Circulation in Fish

-Excretion and Osmosis

-Reproduction Reproductive System in Fish

-Nervous and Nervous System

-Recurrent System of Fish

-Respiratory System of Fish

Respiratory System of Fish

-Nerves and senses

-Endocrine

Headed, cold-blooded vertebrates that are fully aquatic and breathe in water, including round gobies, planktivores, and higher gilled aquatic vertebrates with cartilaginous or scleractinian skeletons

1. Breathe through gills

2. Use fins for locomotion

3. Have scales on their surfaces that secrete mucus and reduce water Resistance

4. Lateral line to sense the current

Fish :

I. Chondrichthyes

This lineage is the lowest class of extant fishes, there are about 200 species in the world and 140 species in China, the vast majority of which live in the sea.

The main characteristics are:

1) Lifelong absence of hard bones, the endoskeleton is composed of cartilage.

②The body surface is mostly covered with tatty scales.

③ Gill spacers are well developed and there is no gill cover.

④Crooked caudal fin. This lineage *** is divided into two subclasses, namely, the subclass Plate Gill and the subclass Holothuroidea.

II. Osteichthyes

The Osteichthyes is the largest group of extant fishes in the world, with more than 20,000 species, most of which live in marine waters and some in fresh water.

The main characteristics are:

①Skeletons are hardened to varying degrees into sclerites.

② The body surface is covered with hard, rounded or pectinate scales, and a few species are degenerately scale-free. The mucous glands of the skin are well developed.

3) Gill septa partially or completely degenerated, gills do not open directly to the outside of the body, there is a bony gill cover cover, the water from the gill slits, through the gill cover of the posterior edge of the drain, most have a swim bladder.

④The tail of the fish is often positively shaped, but there are also proto-tails or crooked tails.

⑤Most are fertilized in vitro and are oviparous, while a few have metamorphosis in development.

Birds:Most fly. The body surface is covered with feathers, usually the forelimbs become wings (some species have degenerated wings), the bones are porous and filled with gas; the heart has two atria and two ventricles. Body temperature is constant. The respiratory organs, in addition to the lungs, have air sacs formed by projections from the lung walls, which are used to assist the lungs in double respiration. Oviparous.

3. Reptiles have inner and middle ears, lay amniotic eggs, have a neck, have two atria and one ventricle, and the ventricles have incomplete septa

The ****similar characteristics of reptiles are: most have scales (or armor) on their bodies, crawl, and are oviparous (a few are ovoviviparous).

4. Amphibians are animals between fish and reptiles, with a twofold life, which is characterized by: first, thin and moist skin. It consists of epidermis and dermis, containing most of the glands, and many blood vessels are honeycombed under the skin; secondly, the lungs of amphibians are in the form of sacs, which are separated into tiny terminal air chambers. In addition, the amphibian heart is divided into two auricles and one ventricle. Blood circulation is divided into major and minor circulation.

Amphibians are also known as a class of animals, is the history of vertebrate evolution from aquatic to terrestrial transition type, the adult can be adapted to land life, but reproduction and larval development is still inseparable from the water. The main features are: body temperature is not constant; oviparous, larvae live in the water, after metamorphosis, adults can adapt to land life, breathing with lungs, bare and moist skin, no scales, hair and other skin derivatives, mucus glands are abundant, with auxiliary respiratory function. Amphibians originated in the Devonian period about 300 million years ago. In the long process of evolution, fish from water to land gradually self-improvement reached a qualitative change and adapted to the new terrestrial environment, and thus the formation of amphibians, they are the earliest landed tetrapods.

The rich variety of amphibians

There are more than 4,000 species of amphibians *** worldwide. They are divided into three main orders based on their morphology.

Earthropoda (Noctuidae). The main features are: elongated body; no limbs; short or absent tail; earthworm-like shape. There is only one species in China, the Banna salamander. It is the only representative of the order of earthworm salamanders in China.

The order Caudata. The main features are: cylindrical body; four limbs, shorter; life-long long tail and lateral compression; crawling, most species to the aquatic life is dominated by lizard-like, such as giant salamanders, commonly known as "baby fish", is the largest living amphibian.

Anurans. The main features are: short and wide body; limbs, longer; juvenile body with a tail, adult body without a tail, jumping type activity, juvenile body for tadpole, from tadpole to adult development need to undergo metamorphosis process, such as frogs and toads.

Amphibians three purposes of the body shape is different, their defense, diffusion, migration ability is weak, the environment is dependent on a large, although there are a variety of ecological protection of adaptations, but than other classes of vertebrate species are still less, its distribution in addition to the sea and the desert, plains, hills, mountains and plateaus in a variety of habitats have their traces, the highest distribution of the sea level of up to 5,000 meters or so. They are mostly diurnal, more hidden during the day, frequent activities from dusk to dawn, and spend their time in summer hibernation or hibernation when it is hot or cold. With animal food as their mainstay, they have no defense against enemies, and fish, snakes, birds and animals are their natural enemies.

China due to the diversity of biological environment. There are 302 species of amphibians. And Yunnan due to the special geography and complex and diverse natural environment, has a very rich amphibian species, about 100 species. It accounts for 40% of the number of amphibian species in China. Only a few representative species will be introduced in the Animal Diversity-Amphibians later.

5. Soft body, outside the shell, aquatic

Mollusca invertebrates in the number and variety of many, second only to the arthropods. Most marine, a few live on land, fresh water. The familiar snails, mussels, and squid are among their representatives.

The morphology of various types of mollusks varies greatly, but some of their main features are still quite similar. Such as the body is soft, not divided into segments (veneers can be divided into segments), can be divided into head, feet, visceral mass, and the back of the skin expansion of the coat membrane (mantle) four parts. Mollusks are dioecious, and a few are hermaphroditic. Most of them are of the marine type, and develop mostly through the planktonic tambourine larvae and faceplate larvae periods.

The shells secreted by the outer coat gland cells, commonly known as shells, or simply shells. Shells are mostly calcareous shells, with a few having an inner shell, or no shell. Mollusks vary greatly in size, the smallest is less than 1mm, the large ones such as Architeuthis (King Quarry) carapace and the carapace together with the length of the mouth can exceed 36m, is the largest living invertebrates. The geological age of mollusks is from the Cambrian to modern times.