Capture of Prey, Feeding, and Functional Anatomy of the Jaws in Velvet Worms (Onychophora)
Capture of Prey, Feeding, and Functional Anatomy of the Jaws in Velvet Worms (Onychophora)
复制标题
DOI：
10.1093/icb/icv004
复制
发表时间：
2015-08-01
影响因子：
2.6
通讯作者：
Hochberg, Rick
中科院分区：
文献类型：
--
作者：
Mayer, Georg;Oliveira, Ivo S.;Hochberg, Rick
Onychophorans是食肉的陆生无脊椎动物，分布于南半球和赤道附近的热带和温带森林。与缓步动物一起，爪类动物被认为是节肢动物的近亲。其中一个最奇特的特征是它们的狩猎和进食行为。这些动物分泌一种粘性粘液，通过一对粘液乳突喷射出来，缠住猎物。在猎物被固定住之后，它的表皮被一对位于口中的颚刺穿。这些颚构成第二体节的内化附属物，并由中脑支配;因此，它们与螯形动物的螯肢同源，与多足类、甲壳类和昆虫的（第一）触角同源。颌骨也是与躯干的每个行走肢相关的成对爪的系列同源物。颚的结构是相似的代表两个主要的onychophoran亚组，Peripatidae和Peripatopsidae。每一个颚的特点是由一个外部和一个内部刀片;而外部刀片只包括一个大的主齿和多达三个副齿，内部刀片承担许多额外的牙齿。只有在围生体中，这些齿突通过间隙和软膜与内颚的其余部分分开。有爪动物的下颚与大型的足突和使其运动的特殊肌肉有关。与节肢动物的下颌骨不同，爪类动物的下颌是沿着身体的主轴沿着移动的，而不是垂直于身体的主轴。我们的元素分析显示，每个刀片尖端的钙结合增加，这可能提供刚度，而没有证据表明金属或突出矿化的结合。颚的稳定性可能会进一步促进其角质层的锥中锥组织，因为每个刀片由几个堆叠的角质层元素组成。在这项工作中，我们总结了目前的知识onychophorans，这是这些动物的一个特征的颌骨。
Onychophorans are carnivorous, terrestrial invertebrates that occur in tropical and temperate forests of the Southern Hemisphere and around the Equator. Together with tardigrades, onychophorans are regarded as one of the closest relatives of arthropods. One of the most peculiar features of onychophorans is their hunting and feeding behavior. These animals secrete a sticky slime, which is ejected via a pair of slime-papillae, to entangle the prey. After the prey has been immobilized, its cuticle is punctured using a pair of jaws located within the mouth. These jaws constitute internalized appendages of the second body segment and are innervated by the deutocerebrum; thus, they are homologous to the chelicerae of chelicerates, and to the (first) antennae of myriapods, crustaceans, and insects. The jaws are also serial homologs of the paired claws associated with each walking limb of the trunk. The structure of the jaws is similar in representatives of the two major onychophoran subgroups, the Peripatidae and Peripatopsidae. Each jaw is characterized by an outer and an inner blade; while the outer blade consists only of a large principal tooth and up to three accessory teeth, the inner blade bears numerous additional denticles. These denticles are separated from the remaining part of the inner jaw by a diastema and a soft membrane only in peripatids. The onychophoran jaws are associated with large apodemes and specialized muscles that enable their movement. In contrast to the mandibles of arthropods, the onychophoran jaws are moved along, rather than perpendicular to, the main axis of the body. Our elemental analysis reveals an increased incorporation of calcium at the tip of each blade, which might provide rigidity, whereas there is no evidence for incorporation of metal or prominent mineralization. Stability of the jaw might be further facilitated by the cone-in-cone organization of its cuticle, as each blade consists of several stacked, cuticular elements. In this work, we summarize current knowledge on the jaws of onychophorans, which are a characteristic feature of these animals.