What's an arthropod?

Question

What's an arthropod, can you try to explain it as simple as possible? Is human in this category?
Thank you.

Answer 1

Arthropods (Phylum Arthropoda, from the Greek ἄρθρον, meaning joint and ποδός, meaning foot) are the largest phylum of animals and include the insects, arachnids, crustaceans, and others. More than 80% of described living animal species are arthropods [1], with over a million modern species described and a fossil record reaching back to the late proterozoic era. Arthropods are common throughout marine, freshwater, terrestrial, and even aerial environments, as well as including various symbiotic and parasitic forms. They range in size from microscopic plankton (~¼ mm) up to forms several metres long. The largest living arthropod is the Japanese spider crab, with a leg span up to 3½ m (12 ft), and some prehistoric arthropods were even larger, such as Pterygotus and Arthropleura.

Arthropods are characterised by the possession of a segmented body with appendages on each segment. They have a dorsal heart and a ventral nervous system. All arthropods are covered by a hard exoskeleton made of chitin, a polysaccharide, which provides physical protection and resistance to desiccation. Periodically, an arthropod sheds this covering when it moults.

****Basic arthropod structure******

The success of arthropods is related to their hard exoskeleton, segmentation, and jointed appendages. The appendages are used for feeding, sensory reception, defense, and locomotion. The muscle system is more or less assisted by hydraulics originated from the blood pressure created by the heart [2]. The hydraulic system in spiders is especially well developed.

Aquatic arthropods use gills to exchange gases. These gills have an extensive surface area in contact with the surrounding water. Terrestrial arthropods have internal surfaces that are specialised for gas exchange. Insects and most other terrestrial species have tracheal systems: air sacs leading into the body from pores called spiracles in the epidermis cuticle. Others use book lungs, or gills modified for breathing air as seen in species like the coconut crab. Some areas of the legs of soldier crabs are covered with an oxygen absorbing membrane. The gill chambers in terrestrial crabs sometimes have two different structures: one that is gilled and used for breathing underwater, and another specially adapted to take up oxygen from the air (a pseudolung). Arthropods also have a complete digestive system with both a mouth and anus.

Arthropods have an open circulatory system. Haemolymph containing haemocyanin, a copper-based oxygen-carrying protein (the copper makes the blood blue, unlike humans that use hemoglobin which uses iron that makes it red), is propelled by a series of hearts into the body cavity where it comes in direct contact with the tissues. Arthropods are protostomes. There is a coelom, but it is reduced to a tiny cavity around the reproductive and excretory organs, and the dominant body cavity is a haemocoel, filled with haemolymph which bathes the organs directly. The arthropod body is divided into a series of distinct segments, plus a pre-segmental acron which usually supports compound and simple eyes and a post-segmental telson. These are grouped into distinct, specialised body regions called tagmata. Each segment, at least primitively, supports a pair of appendages.

The success of arthropods is related to their hard exoskeleton, segmentation, and jointed appendages. The appendages are used for feeding, sensory reception, defense, and locomotion. The muscle system is more or less assisted by hydraulics originated from the blood pressure created by the heart [2]. The hydraulic system in spiders is especially well developed.

Aquatic arthropods use gills to exchange gases. These gills have an extensive surface area in contact with the surrounding water. Terrestrial arthropods have internal surfaces that are specialised for gas exchange. Insects and most other terrestrial species have tracheal systems: air sacs leading into the body from pores called spiracles in the epidermis cuticle. Others use book lungs, or gills modified for breathing air as seen in species like the coconut crab. Some areas of the legs of soldier crabs are covered with an oxygen absorbing membrane. The gill chambers in terrestrial crabs sometimes have two different structures: one that is gilled and used for breathing underwater, and another specially adapted to take up oxygen from the air (a pseudolung). Arthropods also have a complete digestive system with both a mouth and anus.

Arthropods have an open circulatory system. Haemolymph containing haemocyanin, a copper-based oxygen-carrying protein (the copper makes the blood blue, unlike humans that use hemoglobin which uses iron that makes it red), is propelled by a series of hearts into the body cavity where it comes in direct contact with the tissues. Arthropods are protostomes. There is a coelom, but it is reduced to a tiny cavity around the reproductive and excretory organs, and the dominant body cavity is a haemocoel, filled with haemolymph which bathes the organs directly. The arthropod body is divided into a series of distinct segments, plus a pre-segmental acron which usually supports compound and simple eyes and a post-segmental telson. These are grouped into distinct, specialised body regions called tagmata. Each segment, at least primitively, supports a pair of appendages.

*****Classification of arthropods*****
1.Trilobites are a group of formerly numerous marine animals that died in the mass extinction at the end of the Permian-Triassic extinction event.
2. Chelicerates include spiders, mites, scorpions and related organisms. They are characterised by the presence of chelicerae.
3.Myriapods comprise millipedes and centipedes and their relatives and have many body segments, each bearing one or two pairs of legs. They are sometimes grouped with the hexapods.
4.Hexapods comprise insects and three small orders of insect-like animals with six thoracic legs. They are sometimes grouped with the myriapods, in a group called Uniramia, though genetic evidence tends to support a closer relationship between hexapods and crustaceans.
6.Crustaceans are primarily marine (a notable exception being woodlice) and are characterised by having biramous appendages. They include lobsters, crabs, barnacles, and many others.

Answer 2

Arthropoda is a phylum of animals. Some specific charateristics are segmented bodies (head, thorax, and abdomen), they have an exoskeleton, and their name literally means that they have jointed legs. About 80% of all known species on earth are arthropods, and there are probably tens of millions of undescribed species of arthropods. These animals include everything from lobsters to beetles.

Humans on the other hand are in the phylum mammalia.

I hope my explanation was clear and easy to understand =]

Answer 3

No, humans are not arthopods. Think of crabs, etc.
Technically, they are invertebrate animals of the phylum Arthropoda, including the insects, crustaceans, arachnids, and myriapods, that are characterized by a chitinous exoskeleton and a segmented body to which jointed appendages are articulated in pairs. So spiders, and bugs are arthropods.

Answer 4

An arthropods are animals that has a hard shells. Human have no hard hells on their body.

Answer 5

"All" is a dangerous word. Barnacles are arthropods. Larvae of barnacles in the genus Sacculina are endoparasites of crabs, and they lack an exoskeleton. So the answer to your question is "false."

Answer 6

They have an exoskeleton and body segments.=P