Aedes Mosquitoes: The Universal Vector
Jagriti Narang, Manika Khanuja in Small Bite, Big Threat, 2020
Sometimes after 48–72 h, the fourth instar larvae stop feeding. The head, thorax, and the elongated appendages now fuse to form a structure termed “cephalothorax.” The abdomen part terminates into two paddles, which help in propulsion. The pupae appear to be “comma shaped,” lying over the water surface (Fig. 1.9) (Gubler, 1989). Initially they appear brown but change to black in color due to continuous exposure to air. The cephalothorax is formed when an air bubble gets enclosed between the appendages. This helps the pupae to float on the water surface. The pupa does not feed but only breathes through respiratory trumpets (Nelson, 1986). As far as the organs are concerned, some of the larval organs such as alimentary canal get destroyed during the development stage, while others such as heart and fat body remain as such in the pupal stage. Under laboratory conditions, when the process of development of pupae to adult form is near, a “glass gola” is placed over the beaker. The glass gola is an elliptical structure (resembles a traditional candle/lamp shade) open on both sides such that its one end fits on the beaker and the other open end is covered by a muslin cloth (for proper aeration). The gola provides a resting place for the adults and helps in collecting the adults emerged (CDC, 2016) (Fig. 1.10).
Biology and Distribution of Spiders of Medical Importance
Jürg Meier, Julian White in Handbook of: Clinical Toxicology of Animal Venoms and Poisons, 2017
The body of the spider consists of a prosoma (cephalothorax) and an opisthosoma (abdomen); they are connected together by a narrow stalk, the petiolus or pedicel. The cephalothorax is protected dorsally by a hard plate, the carapace, and ventrally by the sternum, labium and coxae of the legs. The eyes are situated on the cephalothorax, sometimes grouped upon a tubercle or disposed in rows. The cephalothorax can also present a thoraxic groove and radial furrows; sometimes it is possible to distinguish a cephalic and a thoracic region. The chelicerae are situated in front of the cephalothorax or below.
Interactions between sea lice and their hosts
G. F. Wiegertjes, G. Flik in Host-Parasite Interactions, 2004
All of the developmental stages of sea lice use modified second antennae, maxillae and to a lesser extent the maxillipeds, for host attachment. These appendages are capable of piercing host tissues enabling a secure attachment. In the chalimus stages sea lice also rely upon the frontal filament to maintain their position on the host, especially between moults. In addition to the above-mentioned appendages and structures the mobile preadult and adult stages also use their post antennary processes, sternal furca and cephalothorax for attachment (Jønsdøttir et al., 1992; Kabata, 1979; Kabata and Hewitt, 1971) (Figure 2). The cephalothorax or dorsal shield is formed by the fusion of the cephalon and thoraxic segments up to and including the segment that bears the third leg (Kabata, 1979; Kabata and Hewitt, 1971). In sea lice the third leg is modified to form a transverse barrier that closes off the posterior margin of the cephalothorax (Kabata and Hewitt, 1971). A thin strip of membrane fringes the margins of this barrier. Another thin flexible membrane called the marginal membrane fringes the margin of the cephalothorax (Figure 2). Both of these membranes enable a tight seal to be produced between the copepod’s body and the skin of the host, allowing the cephalothorax to essentially function as a suction cup. Two openings on the posterior margin of the cephalothorax, the posterior sinuses, are equipped with membranes that serve as oneway valves allowing water to be expelled from beneath the cephalothorax. Co-ordinated movements of the first and second leg push jets of water through these valves, causing both downward and forward thrust. This thrust allows the copepod to move forward while at the same time pressing it against the surface of the host. Replacement water passes under the frontal plates that form the anterior margin of the cephalothorax (Kabata and Hewitt, 1971). In pre-adult and adult stages of Caligus spp. cup-like suckers, the lunnules, are present on the anterior margin of the cephalothorax. These structures are thought to play a secondary role in attachment although their importance as attachment organs has not been conclusively demonstrated (Kabata, 1979).
Body condition and energy content of the shore crab Carcinus maenas L. in a temperate coastal system: the cost of barnacle epibiosis
Published in Biofouling, 2022
Joana Campos, Felipe Ribas, Ana Bio, Vânia Freitas, Allan T. Souza, Henk W. van der Veer
Most epibiont species do not settle exclusively on one host species or exhibit obligate epibiosis (Wahl and Mark 1999; Fernandez-Leborans 2010; Leonard et al. 2017). In the Wadden Sea, epibiosis by B. crenatus also occurs on the blue mussel Mytilus edulis, albeit to a lesser extent (10% of subtidal mussels, Buschbaum and Saier 2001), and on the periwinkle Littorina littorea, where it can affect 86% of the population (Buschbaum and Reise 1999). Barnacles B. crenatus are also the most common epibionts found on the cephalothorax of the spider crab Maja squinado in Spanish waters (Parapar et al. 1997), in Cancer spp. from British Columbia (C. gracilis, 42%; C. magister, 64%; and C. productus, 79%; McGaw 2006), and in the red king crab Paralithodes camtschaticus (43%, Dvoretsky and Dvoretsky 2009). Elsewhere, other hard-shelled organisms may harbour B. crenatus epibionts (e.g. Barnes and Bagenal 1951; Dick et al. 1998; Giri and Wicksten 2001; Fernandez-Leborans and Gabilondo 2007; Savoie et al. 2007; Dvoretsky and Dvoretsky 2021) to an unknown extent.