Calcarea Hexactinellida Demospongiae The sponges or poriferans (from Latin porus "pore" and ferre "to bear") are animals of the phylum Porifera. They are primitive, sessile, mostly marine, waterdwelling filter feeders that pump water through their matrix to filter out particulates of food matter. Sponges are among the simplest of animals, with partially differentiated tissues but without muscles, nerves, or internal organs. In some ways they are closer to being cell colonies ...

Including:

• Sponge - Anatomy
• Sponge - Taxonomy
• Sponge - Reproduction
• Sponge - Ecology
• Sponge - Skeleton as absorbent
• Sponge - Geological history

Read more here: » Sponge: Encyclopedia - Sponge

See also:

Sponge, Sponge - Anatomy, Sponge - Taxonomy, Sponge - Reproduction, Sponge - Ecology, Sponge - Skeleton as absorbent, Sponge - Geological history

Read more here: » Sponge: Encyclopedia II - Sponge - Anatomy

Modern sponges are predominantly marine, with some species adapted to freshwater environments, ranging from the inter-tidal zone to depths of 6,000 metres (19,680 feet). Certain types of sponges are limited in the range of depths at which they are found. Sponges are worldwide in their distribution, and range from waters of the polar regions to the tropical regions. Sponges are most abundant in both numbers of individuals and species in warmer waters. Their bodies are porous and they feed by filtering micro-organisms from the water. They lack any internal organs, a nervous system, or circulatory and digestive systems, such as are found i ...

See also:

Sponge, Sponge - Anatomy, Sponge - Taxonomy, Sponge - Reproduction, Sponge - Ecology, Sponge - Skeleton as absorbent, Sponge - Geological history

Read more here: » Sponge: Encyclopedia II - Sponge - Ecology

A corpus cavernosum is one of a pair of a sponge-like regions of erectile tissue which contain most of the blood in the male penis during erection. There are corresponding structures and functions in the female clitoris. The term literally means "cave-like body" (plural: corpora cavernosa). Corpus cavernosum - Male anatomy. The corpus cavernosum and corpus spongiosum are three expandable erectile tissues along the length of the penis which fill with blood during erection. The two corpora cave ...

Including:

• Corpus cavernosum - Male anatomy
• Corpus cavernosum - Female anatomy

Read more here: » Corpus cavernosum: Encyclopedia - Corpus cavernosum

In anatomy, the urethra is a tube which connects the urinary bladder to the outside of the body. The urethra has an excretory function in both sexes, to pass urine to the outside, and also a reproductive function in the male, as a passage for sperm. The external urethral sphincter is a smooth muscle that allows voluntary control over urination. Urethra - Anatomy. Men have a longer urethra than women. This means that women tend to be more susceptible to infections of the bladder (cystitis) and the uri ...

Including:

• Urethra - Anatomy
• Urethra - Histology
• Urethra - Medical problems of the urethra
• Urethra - Related topics

Read more here: » Urethra: Encyclopedia - Urethra

A sex organ, or primary sexual characteristic, narrowly defined, is any of those parts of the body (which are not always bodily organs according to the strict definition) which are involved in sexual reproduction and constitute the reproductive system in a complex organism; namely: Male: penis (notably the glans penis and foreskin), prepuce, testicles, scrotum, prostate, seminal vesicles, epididymis, Cowper's glands Female: vulva (notably the clitoris and labia), vagina, cervix, uterus, Fallopian tubes, ova ...

Including:

• Sex organ - Anatomical terms related to sex

Read more here: » Sex organ: Encyclopedia - Sex organ

See article below. Dolphins are aquatic mammals related to whales and porpoises. The name is from Ancient Greek δελφίς delphis meaning "with a womb", viz. "a 'fish' with a womb". The word is used in a few different ways. It can mean: Any member of the family Delphinidae (oceanic dolphins), Any member of the families Delphinidae and Platanistoidea (oceanic and river dolphins), Any member of the suborder Odontoceti (toothe ...

Including:

• Dolphin - Taxonomy
• Dolphin - Hybrid Dolphins
• Dolphin - Evolution and anatomy of dolphins
• Dolphin - Dolphin behavior
• Dolphin - Feeding
• Dolphin - Dolphin lore

Read more here: » Dolphin: Encyclopedia - Dolphin

The corpus cavernosum and corpus spongiosum are three expandable erectile tissues along the length of the penis which fill with blood during erection. The two corpora cavernosa lie along the penis shaft, from the pubic bones to the head of the penis, where they join. These formations are made of a sponge-like tissue containing irregular blood-filled spaces lined by endothelium and separated by connective tissue septa. The corpus spongiosum is one smaller region along the bottom of the penis, whi ...

See also:

Corpus cavernosum, Corpus cavernosum - Male anatomy, Corpus cavernosum - Female anatomy

Read more here: » Corpus cavernosum: Encyclopedia II - Corpus cavernosum - Male anatomy

Sea star - Reproduction. Most starfish reproduce in a method similar to the sponge. The starfish gather in a group (using environmental signals to coordinate the timing), and release their gametes into the water, where they will hopefully connect with gametes from the opposite sex. After fertilization, there are a variety of ways that the eggs can proceed. Small eggs (those without much yolk) grow into free-swimming larvae which feed on small organisms until they metamorphose into juvenile sea stars and ca ...

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Sea star, Sea star - Distribution, Sea star - External Anatomy, Sea star - Internal Anatomy, Sea star - Digestion and excretion, Sea star - Nervous System, Sea star - Circulation and respiration, Sea star - Behaviour, Sea star - Reproduction, Sea star - Locomotion, Sea star - Regeneration, Sea star - Geological history

Read more here: » Sea star: Encyclopedia II - Sea star - Behaviour

Sea star - Reproduction. Most starfish reproduce in a method similar to the sponge. The starfish gather in a group (using environmental signals to coordinate the timing), metamorphose into juvenile sea stars and can begin living on the ocean floor. Sea stars are developmentally (embryologically) known as deuterostomes. Since echinoderms and chordates share this same embryological pattern, they are thought to be closely related. Nevertheless, as these creatures are invertebrates and not actually fish, most marine biologists are pushing to completely replace the term starfish with sea star. < ...

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Sea star, Sea star - Distribution, Sea star - External Anatomy, Sea star - Internal Anatomy, Sea star - Digestion and excretion, Sea star - Nervous System, Sea star - Circulation and respiration, Sea star - Behaviour, Sea star - Reproduction, Sea star - Locomotion, Sea star - Regeneration, Sea star - Geological history

Read more here: » Sea star: Encyclopedia II - Sea star - Behaviour

The epithelium of the urethra starts off as transitional cells as it exits the bladder. Further along the urethra there are stratified columnar cells, then stratified squamous cells near the external meatus (exit hole). There are small mucus-secreting urethral glands, that help protect the epithelium from the corrosive urine. ...

See also:

Urethra, Urethra - Anatomy, Urethra - Histology, Urethra - Medical problems of the urethra, Urethra - Related topics

Read more here: » Urethra: Encyclopedia II - Urethra - Histology

Men have a longer urethra than women. This means that women tend to be more susceptible to infections of the bladder (cystitis) and the urinary tract. The length of a male's urethra, and the fact it contains a number of bends makes catheterisation more difficult. In the human female, the urethra is about 1-1.5 inches (2.5-4 cm) long and opens in the vulva between the clitoris and the vaginal opening. In the human male, the urethra is about 8 inches (20 cm) long ...

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Urethra, Urethra - Anatomy, Urethra - Histology, Urethra - Medical problems of the urethra, Urethra - Related topics

Read more here: » Urethra: Encyclopedia II - Urethra - Anatomy

Dolphins, along with whales and porpoises, are descendants of land-living mammals, most likely of the Artiodactyl order. Modern dolphin skeletons have two small rod shaped pelvic bones thought to be left-over hind legs. They entered the water roughly 50 million years ago. See evolution of cetaceans for the details. Dolphins have a fusiform body, adapted for fast swimming. The head contains the melon, a round organ used for echolocation. In many species, the jaws are elongated, forming a distinct beak; for some species like the Bottlen ...

See also:

Dolphin, Dolphin - Taxonomy, Dolphin - Hybrid Dolphins, Dolphin - Evolution and anatomy of dolphins, Dolphin - Dolphin behavior, Dolphin - Feeding, Dolphin - Dolphin lore

Read more here: » Dolphin: Encyclopedia II - Dolphin - Evolution and anatomy of dolphins

Sea stars are composed of a central disc with (usually) five arms exhibiting pentaradial symmetry. The mouth is located underneath the sea star on the oral or ventral suface. The spiny upper surface covering the species is called the aboral or dorsal surface. On the aboral surface there is a structure called the madreporite which acts as a water filter and supplies the sea star's water vascular system with water to move. Sea stars have a simple eye at the end of each arm. The eye is able to "see" only differences of light and ...

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Sea star, Sea star - Distribution, Sea star - External Anatomy, Sea star - Internal Anatomy, Sea star - Digestion and excretion, Sea star - Nervous System, Sea star - Circulation and respiration, Sea star - Behaviour, Sea star - Reproduction, Sea star - Locomotion, Sea star - Regeneration, Sea star - Geological history

Read more here: » Sea star: Encyclopedia II - Sea star - External Anatomy

Sea stars are composed of a central disc from which arms sprout in radial symmetry. Most starfish have five arms, however some have more or less; in fact some starfish can have different numbers of legs within one species. The mouth is located underneath the sea star on the oral or ventral suface, while the anus is located on the top of the animal. The spiny upper surface covering the species is called the aboral or dorsal surface. On the aboral surface there is a structure called the madreporite which acts as a water filter and supplies the sea sta ...

See also:

Sea star, Sea star - Distribution, Sea star - External Anatomy, Sea star - Internal Anatomy, Sea star - Digestion and excretion, Sea star - Nervous System, Sea star - Circulation and respiration, Sea star - Behaviour, Sea star - Reproduction, Sea star - Locomotion, Sea star - Regeneration, Sea star - Geological history

Read more here: » Sea star: Encyclopedia II - Sea star - External Anatomy

The body cavity also contains the water vascular system that operates the tube feet, and the hemal system. Hemal channels form rings around the mouth (the oral hemal ring), closer to the top of the starfish and around the digestive system (the gastric hemal ring). The axial sinus, a portion of the body cavity, connects the three rings. Each ray also has hemal channels running next to the gonads. < ...

See also:

Sea star, Sea star - Distribution, Sea star - External Anatomy, Sea star - Internal Anatomy, Sea star - Digestion and excretion, Sea star - Nervous System, Sea star - Circulation and respiration, Sea star - Behaviour, Sea star - Reproduction, Sea star - Locomotion, Sea star - Regeneration, Sea star - Geological history

Read more here: » Sea star: Encyclopedia II - Sea star - Internal Anatomy

Evidence of evolution - Serological studies. Evidence of evolution - Evolution of widely distributed proteins. ...

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Evidence of evolution, Evidence of evolution - Evidence from palaeontology, Evidence of evolution - Fossil records, Evidence of evolution - Evolutionary development of modern horse, Evidence of evolution - Limitations, Evidence of evolution - Living fossils, Evidence of evolution - Evidence from comparative anatomy, Evidence of evolution - Homologous structures and divergent adaptive evolution, Evidence of evolution - Analogous structures and convergent evolution, Evidence of evolution - Vestigial organs, Evidence of evolution - Evidence from geographical distribution, Evidence of evolution - Evidence from comparative embryology, Evidence of evolution - Evidence from comparative physiology and biochemistry, Evidence of evolution - Serological studies, Evidence of evolution - Evolution of widely distributed proteins

Read more here: » Evidence of evolution: Encyclopedia II - Evidence of evolution - Evidence from comparative physiology and biochemistry

Marine biology - Microscopic life. Microscopic life undersea is incredibly varied and still poorly understood. For example, at one end of the scale, the role of viruses in marine ecosystems is barely being explored even in the beginning of the 21st century. The role of phytoplankton is better understood due to their critical position as the most numerous primary producers on Earth. Phytoplankton are categorized into cyanobacteria (also called blue-green algae/bacteria), various types of algae: red, green, ...

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Marine biology, Marine biology - Overview, Marine biology - Subfields, Marine biology - Related fields, Marine biology - Lifeforms, Marine biology - Microscopic life, Marine biology - Plant life, Marine biology - Other sea life, Marine biology - Fish, Marine biology - Marine mammals, Marine biology - Reefs, Marine biology - Deep sea and trenches, Marine biology - How oceanic factors affect distribution of various organisms, Marine biology - Famous marine biologists

Read more here: » Marine biology: Encyclopedia II - Marine biology - Lifeforms

Marine biology - Microscopic life. Microscopic life undersea is incredibly varied and still poorly understood. For example, the role of viruses in marine ecosystems is barely being explored even in the beginning of the 21st century. The role of phytoplankton is better understood due to their critical position as the most numerous primary producers on Earth. Phytoplankton are categorized into cyanobacteria (also called blue-green algae/bacteria), various types of algae: red, green, brown, and yellow-green, diatoms, dinoflagellates, euglenoids, coccolithophorids, cryptomonads, crysomonads, chlorom ...

See also:

Marine biology, Marine biology - Overview, Marine biology - Subfields, Marine biology - Related fields, Marine biology - Lifeforms, Marine biology - Microscopic life, Marine biology - Plant life, Marine biology - Other sea life, Marine biology - Fish, Marine biology - Marine mammals, Marine biology - Reefs, Marine biology - Deep sea and trenches, Marine biology - How oceanic factors affect distribution of various organisms, Marine biology - Famous marine biologists

Read more here: » Marine biology: Encyclopedia II - Marine biology - Lifeforms

Comparative study of the anatomy of groups of animals or plants reveals that certain structural features are basically similar. For example, the basic structure of all flowers consists of sepals, petals, stigma, style and ovary; yet the size, colour, number of parts and specific structure are different for each individual species. Evidence of evolution - Homologous structures and divergent adaptive evolution. If widely separated groups of organisms are originated from a common ancestry, they are expected t ...

See also:

Evidence of evolution, Evidence of evolution - Evidence from palaeontology, Evidence of evolution - Fossil records, Evidence of evolution - Evolutionary development of modern horse, Evidence of evolution - Limitations, Evidence of evolution - Living fossils, Evidence of evolution - Evidence from comparative anatomy, Evidence of evolution - Homologous structures and divergent adaptive evolution, Evidence of evolution - Analogous structures and convergent evolution, Evidence of evolution - Vestigial organs, Evidence of evolution - Evidence from geographical distribution, Evidence of evolution - Evidence from comparative embryology, Evidence of evolution - Evidence from comparative physiology and biochemistry, Evidence of evolution - Serological studies, Evidence of evolution - Evolution of widely distributed proteins

Read more here: » Evidence of evolution: Encyclopedia II - Evidence of evolution - Evidence from comparative anatomy