In some primitive cartilaginous fishes, such as the spiny dogfish or mud shark ( Squalus acanthias ), there is a terminal nerve numbered zero, since it exits the brain before the traditionally designated first cranial nerve.

The spiny dogfish has the longest lifespan at more than 100 years.

For example, both the spiny dogfish and the Port Jackson shark have spines in their dorsal fins which are capable of secreting poison.

Dissection of a spiny dogfish.

:* Squalidae ( dogfish sharks ), particularly the spiny dogfish ( Squalus acanthias )

Cephalopods, particularly squid, also form an important component of its diet, while smaller sharks such as spiny dogfish ( Squalus acanthias ) and tope sharks ( Galeorhinus galeus ) are rarely taken.

The spiny dogfish has dorsal spines, no anal fin, and white spot along its back.

A mountain of spiny dogfish.

In the recent past the European market for spiny dogfish has increased dramatically, which led to the overfishing and decline of the species.

This drastic increase led to the creation and implementation of many fishery management policies placing restrictions on the fishing of spiny dogfish.

In 2010, Greenpeace International added the spiny dogfish to its seafood red list.

This species feeds on a variety of benthic and pelagic bony fishes, including hake, flounders, rockfishes, lingcod, topsmelt, mackerel, and herring, and on cartilaginous fishes, including elephantfishes ( Callorhinchus ), spiny dogfish ( Squalus acanthias ), young bluntnose sixgill sharks ( Hexanchus griseus ), and ghost catshark ( Apristurus ) egg cases.

The dish can be one of many species of small shark, including the spiny dogfish ( Squalus acanthias ) or the bull huss ( Scyliorhinus stellaris ).

However, the spiny dogfish is now an endangered species due to overfishing, and is classed as Vulnerable on the IUCN Redlist and the North East Atlantic population as Critically Endangered.

Many fishes, particularly eel-shaped fishes such as true eels, moray eels, and spiny eels, are capable of burrowing through sand or mud.

Natural predators of the California spiny lobster include bony fish such as the California sheepshead, giant sea bass and cabezone, sharks including the horn shark and leopard shark, octopuses and sea otters.

These can trap enemies, who are defeated if the bubble is then burst by the player's spiny back.

The word cactus derives, through Latin, from the Ancient Greek ( kaktos ), a name originally used for a spiny plant whose identity is not certain.

The fruit is a spiny capsule 4 – 10 cm long and 2 – 6 cm broad, splitting open when ripe to release the numerous seeds.

Thorn forest, a dense forest of low stature with a high frequency of thorny or spiny species, is found where drought is prolonged, and especially where grazing animals are plentiful.

The family Didiereaceae, composed of four genera and 11 species, is limited to the spiny forests of southwestern Madagascar.

A better etymology perhaps is from Latin sudis, plural sudes, " spines ", which can be used of spiny fish or spiny terrain.

The word " Echinoderm " is derived from the Greek ἐχινοδέρματα ( echinodermata ), plural of ἐχινόδερμα ( echinoderma ), " spiny skin " from ἐχινός ( echinos ), " sea-urchin ", originally " hedgehog ," and δέρμα ( derma ), " skin ".

The most notable feature of the acanthocephala is the presence of an anterior, protrudible proboscis that is usually covered with spiny hooks ( hence the common name: thorny headed worm ).

In Australia, New Zealand and South Africa, the term crayfish or cray generally refers to a saltwater spiny lobster, of the genus Jasus that is indigenous to much of southern Oceania, while the freshwater species are usually called yabby or, from the indigenous Australian and Māori names for the animal respectively, or by other names specific to each species.

The stem is often spiny.

A hedgehog is any of the spiny mammals of the subfamily Erinaceinae and the order Erinaceomorpha.

There is also an anal fin, which is also considered spiny, and a caudal fin.

The spiny first dorsal fin is normally folded back in a groove, as are its pectoral fins.

Indeed, based on the canonical anatomofunctional model of basal ganglia, nigrostriatal dopamine is able to modulate the motor loop by acting on dopaminergic receptors located on striatal GABAergic medium spiny neurons.

Their shell, or " test ", is round and spiny, typically from across.

The name " urchin " is an old name for the round spiny hedgehogs that sea urchins resemble.

alt = Photo of black spiny animal next to fish whose head is embedded in animal

The fruit is contained in a spiny ( very sharp ) cupule in diameter, also called " bur " or " burr ".

The American chestnut is a prolific bearer of nuts, usually with three nuts enclosed in each spiny, green burr, and lined in tan velvet.

Eryngium is a genus in the family Apiaceae of about 230 species of annuals and perennials with hairless and usually spiny leaves, and dome-shaped umbels of flowers resembling those of thistles.

There are two dorsal fins, the first one spiny and the second soft.

Fruits lack endosperm and lie in a scaly or spiny husk that may or may not enclose the entire nut, which may consist of one to seven seeds.

The subgenus Grossularia differs somewhat from currants, chiefly in their spiny stems, and in that their flowers grow one to three together on short stems, not in racemes.

* The spiny and soft ray portions of the dorsal fin are continuous, so there is only one long fin instead of two short separate ones as for the wreckfish Polyprion americanus, scup Stenotomus chrysops, rose fish Sebastes marinus, cunner Tautogolabrus adspersus, striped bass Morone saxatilis.

In some parts of Asia, swamp eels and one species of spiny eel, Mastacembelus erythrotaenia, are valued as food and sometimes are kept in ponds or rice fields.

As the family Halosauridae, halosaurs are one of two families within the order Notacanthiformes ; the other being the deep-sea spiny eels.

The long-beaked echidnas make up one of the two genera ( genus Zaglossus ) of echidnas, spiny monotremes that lives in New Guinea.

The fat-tailed dwarf lemur ( Cheirogaleus medius ), also known as the lesser dwarf lemur, western fat-tailed dwarf lemur, or spiny forest dwarf lemur, is one of the smallest primates.

The mammalian fauna of the region includes six species of marsupials, three muskrats, at least 58 bats, three primates, seven edentates, two rabbits, one ground hog, three species of squirrels, one species of spiny mouse, at least 15 species of long-tailed rats and mice ( family Muridae ); one species of porcupine, one species of agouti, one paca, two canids, five mustelids, four species of procyonids, six species of felines, two species of wild pigs, two species of deer, and one tapir.

The California spiny lobster is one of the largest spiny lobster species, and grows up to long, but does not usually exceed.

Apical dendrites are one of two primary categories of dendrites, and they distinguish the pyramidal cells from spiny stellate cells in the cortices.