Millipedes belong to Class Diplopoda and are more rigid arthropods distinguishable by their subcylindrical shape. Centipedes have one pair of legs per body segment, while millipedes have two pairs. While most centipedes are known for their speed, millipedes move slowly and burrow. Centipedes and millipedes also vary in diet: centipedes are carnivores and millipedes are primarily detritivores.
Centipedes are carnivorous and kill their prey by injecting them with venom. Millipedes feed primarily on decaying organic matter and they may eat the roots and leaves of seedling plants. Millipedes are ecologically esteemed as agents of microbial decomposition and soil nutrient cycles. Centipedes have maxillipeds with which they attack prey. These are the venomous modified legs of the centipede's first segment and can be used in defense, as well.
A centipede bite can kill small prey, but typically is not life threatening to humans. In the absence of stinging structures, millipedes employ defensive secretions in order to protect themselves from predators.
These secretions are produced by their segmental defensive glands. A millipede will also curl its body as a defense mechanism. While centipedes sometimes bite humans, it is rare that their venom will produce a severe reaction. However, small children and those with other insect allergies should be watched carefully following a centipede bite. In the event of bite-related medical concerns, a medical professional should be contacted at once. The class name refers to the lip- like appearance of the fused bases of these appendages.
Eyes may be present or absent. Centipedes are elongate and flattened. They are usually found in somewhat protected places, such as in leaf litter, in the soil, under bark, or in rotten logs. One species is commonly found in houses and other buildings.
Centipedes are predatory and feed on insects, spiders, and other small animals. The larger centipedes can bite humans, but the bite is not serious and is no more painful that the sting of a bee or wasp. The common small centipedes of Nebraska are harmless to man. Overall, centipedes are beneficial natural enemies of insects. Class Diplopoda dip-low-po-da , the millipedes.
Two tagmata head and trunk. One pair of antennae , usually having seven segments. Two pairs of legs on most trunk segments 30 or more pairs total. Mouthparts: one pair of mandibles, and one pair of maxillae. Eyes are usually present. Millipedes are usually cylindrical sometimes slightly flattened.
Except for the first three trunk segments, each segment has two pairs of short legs. Millipedes are found in damp places such as the soil, leaf litter, or under logs and stones. Most millipedes are beneficial scavengers of decaying plant material. A few attack living plants and are sometimes pests.
Even fewer are predacious. Millipedes do not bite man, but many give off a foul-smelling fluid containing hydrogen cyanide which can be strong enough to kill insects placed in a jar with a millipede. Class Insecta in- sec-ta , the insects. Three pairs of legs.
May have wings, either one or two pairs. Insects are the most abundant life form now known to science. Around 1,, species have been described and named. That is more than all the other known animals put together. Skip to main content. Classification, Nomenclature, and Identification of Insects and their Relatives Classification: Classifying involves grouping things into categories based on similar characteristics.
Exoskeleton containing chitin 2. Body bilaterally symmetrical 3. Jointed appendages 5. These jointed appendages variously specialized for feeding, locomotion, sensing Key to the Adults of the Common Classes of Arthropoda 1a. Two pairs of antennae one pair may be reduced, difficult to see ; Number of legs variable. Class Crustacea , go to 2 1b.
Two distinct body regions cephlothorax and abdomen ; Five pairs of thoracic legs. Three distinct body regions head, thorax, abdomen ; Seven pairs of thoracic legs.
No antennae; Two distinct body regions cephlothorax and abdomen ; Four pairs of legs;. Three distinct body regions head, thorax, abdomen ; Three pairs of thoracic legs.
Class Insecta 4b. Two pairs of antennae can be difficult to see both pairs Five pairs of legs on the cephlothorax, the first pair usually with a large claw Order Isopoda eye-so-po-da. Three tagmata head, thorax and abdomen Two pairs of antennae: first pair is greatly reduced , seldom noticed Seven pairs of legs , one pair on each thoracic segment Abdomen small, more or less fused.
Common orders of Arachnida include: Order Araneae a-ran-e-uh , the spiders. Two tagmata cephlothorax and abdomen No antennae Abdomen joined to cephlothorax by slender pedicel Four pairs of legs Mouthparts: One pair chelicerae and one pair of pedipalps Eyes simple ocelli. Usually eight, sometimes fewer Poison apparatus opens on the fangs of the chelicerae Silk apparatus always present at end of abdomen, below anus This is a large order, having about species in North America. In Nebraska, the black widow and the brown recluse are the only seriously venomous spiders Order Acari ak-a-ri , the mites and ticks.
Two tagmata cephlothorax and abdomen No antennae. Four pairs of legs in adults; only three pairs at hatching Ticks and mites occur just about anywhere animal life is found. Two tagmata cephlothorax and abdomen No antennae No pedicel between cephlothorax and abdomen Four pairs of legs on cephlothorax One pair of chelicerae and one pair of long, pincher-like pedipalpsAbdomen with seven broad segments anteriorly, followed by five narrower segments which end with a large stinger.
Two tagmata head and trunk One pair of antennae with 14 or more segments One pair of legs per trunk segment. Mouthparts: one pair of mandibles and two pairs of maxillae Appendages on the first trunk segment are clawlike poison jaws or fangs with which centipedes paralyze their prey.
Two tagmata head and trunk One pair of antennae , usually having seven segments Two pairs of legs on most trunk segments 30 or more pairs total Mouthparts: one pair of mandibles, and one pair of maxillae Eyes are usually present Millipedes are usually cylindrical sometimes slightly flattened.
Three tagmata head, thorax and abdomen One pair of antennae Three pairs of legs May have wings, either one or two pairs Insects are the most abundant life form now known to science. While the animal molts, it is especially vulnerable - just ask a plate of soft-shelled crabs! Arthropods have segmented bodies, like the annelid worms. These segments have become specialized, however, with one pair of jointed appendages added to each segment. Among living arthropods, the millipedes most closely suggest what the ancestral arthropod might have looked like.
Arthropod segments have also fused together into functional units called tagma. This process of segment fusion, or tagmosis , usually results in an arthropod body that consists of three major sections, a head, thorax, and abdomen. Sometimes the head and thorax are fused together into a cephalothorax.
Each of these body sections still bear the appendages that went with it, though these appendages are often highly modified. Arthropods are very highly cephalized, often with intricate mouthparts and elaborate sensory organs, including statocysts , antennae, simple eyes and compound eyes.
Sensitive hairs on the surface of the body can detect touch, water currents, or chemicals. Their nervous systems are highly developed, with chains of ganglia serving various parts of the body, and three fused pairs of cerebral ganglia forming a brain. Aquatic arthropods respire with gills.
Terrestrial forms rely on diffusion through tiny tubes called trachea. Trachea are cuticle-lined air ducts that branch throughout the body, and open in tiny holes called spiracles , located along the abdomen. Insects can open and close these spiracles, to conserve water that would otherwise be lost to evaporation from the open tubes.
Their reliance on diffusion for respiration is one of the reasons that insects are small. Arthropods excrete by means of malphigian tubules , projections of the digestive tract that help conserve water. Terrestrial forms excrete nitrogen as uric acid , as do birds. Their waste is nearly dry, a superb adaptation to life on land. Arthropods have an open circulatory system, and separate sexes.
Fertilization is usually internal, another adaptation for terrestrial life. Males and females often show pronounced sexual dimorphism. Order Orthoptera - grasshoppers, crickets, roaches.
In chelicerates, the first pair of appendages are called chelicerae, and are modified to manipulate food. They are often modified as fangs or pincers.
Chelicerates lack antennae. Horseshoe crabs have larvae that are very similar to trilobites, and they may be descendants of this long vanished group. Horseshoe crabs are nocturnal, feeding on annelids and molluscs. They swim on their backs, or walk upright on five pairs of walking legs. They live in the deep ocean, migrating inshore in large numbers in the spring to mate on the beaches during moonlight and high tide - much like undergraduates on Spring Break.
This very successful group of arthropods have four pair of walking legs 8 legs. The first pair of appendages are the chelicerae , and the second pair are pedipalps , appendages modified for sensory functions or for manipulating prey. They are mostly carnivorous many mites are herbivores. Most secrete powerful digestive enzymes which are injected into the prey to liquify it. Once dissolved in its own epidermis, the prey is sipped like a root beer float. Order Scorpiones 2, sp. Scorpions date back to the Silurian, about mya, and may be the first terrestrial arthropods.
Order Araneae 32, sp. Not all spiders spin webs. Wolf spiders are the tigers of the leaf litter, and the common jumping spider leaps several times its body length to catch its prey. Spiders use pedipalps as copulatory organs. Spiders breathe by book lungs. Order Acari - 30, sp. Most are very tiny, less than 1 mm long.
The thorax and head are fused into a single unit cephalothorax. Order Opiliones 5, sp. It has an oval body with extremely long legs, which they frequently lose in various accidents and brushes with predators. They are predators, herbivores, and scavengers. Look at them closely next time you see one. They carry their eyes atop a little tower on their back weird! Crustaceans are mostly marine, and dominate the ocean to the same degree that insects dominate the land and air.
Despite their aquatic diversity, there are very few terrestrial crustaceans, just as there are very few truly aquatic insects. Crustaceans have biramous appendages. Each leg has an additional process, like a little miniature leg branching off from the main leg.
Many groups of crustaceans have lost this extra appendage during subsequent evolution. The Order Decapoda have five pair of walking legs, and include the familiar crabs, lobsters, and crayfish. The first pair of appendages are usually modified as antennae.
Crustaceans have two pair of antennae. Another set of anterior appendages are modified as mandibles, which function in grasping, biting, and chewing food. Male crayfish also use one pair of legs as a copulatory organ. All crustaceans share a common type of larva called a nauplius larva. They are one of the few successful terrestrial crustaceans. They feed on decaying vegetation in the leaf litter.
0コメント