Nudibranchs and Sea Snails: Indo-Pacific Field Guide

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These small, ciliated, marine worms were first discovered in mud sediments off the coast of Sweden, and have been the subject of controversy ever since. PHYLUM PLATYHELMINTHES 307 Figure 10.27 Neoöphoran development. (A) The embryo of a typical rhabdocoel has three cell masses with large, vacuolated external yolk cells. (B) A triclad egg cap- sule containing three embryos surrounded by yolk syn- UNCORRECTED PAGE PROOFS The female reproductive system (Figure 10.28B) usual- ly bears a single ovary connected by a short oviduct to a region known as the ootype.

Russian Contributions to Invertebrate Behavior

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Siphonophorans use a swimming bell (nectophore) or a gas-filled float (pneumatophore), or both, to help maintain their position in the water. In all other arachnids, either the sperm are inserted into the female’s body by modi- fied appendages of the male, or they are placed on the ground in spermatophores and then retrieved by the fe- male. Electron microscopic study of the de- velopment of amphioxus, Branchiostoma belcheri tsingtauense: The gastrula.

The Auchenorrhyncha - Homoptera - Of Fennoscandia and

F. Ossiannilsson

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These specialized body regions (e.g., the head, thorax, and abdomen) are called tagmata. The larvae of parasitic species locate a host insect and enter it, wherein they molt into a legless wormlike stage that feeds in the host’s body cavity. In 1997, based on analyses of 18S rDNA sequence data, Aguinaldo et al. proposed an alternative hypothe- sis of arthropod relationships: that there is a clade of an- imals that includes arthropods, tardigrades, onycho- THE EMERGENCE OF THE ARTHROPODS 39 Figure 15.32 A trilobite segment (cross section).

Comparative Endocrinology of the Invertebrates (Contemporary

Leonard Hill

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Cladograms depict only one kind of event: the origin or sequence of ap- pearances of a unique derived character state (synapo- morphy). This material is then incorporated into the general water current moving through the mouth and into the pharynx. Ephyrae are very small animals with characteristical- ly incised bell margins (Figure 8.40C). Perhaps six extant orders, including the Clypeasteroida (sand dollars) and several groups of urchins (e.g., Cassidu- lus, Clypeaster, Dendraster, Echinocardium, Echinodis- cus, Echinolampus, Encope, Fibularia, Lovenia, Maretia, Mellita, Meoma, Metalia, Micropetalon, Spatanga, Urechinus).

Worms Eat Our Garbage: Classroom Activities for a Better

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Most spiders that are capable of these sorts of activities possess intri- cately fashioned “thread clamps” on some or all of the leg tips (Figure 19.12D,E). Includes: Rodents, Hoofed animals, Marsupials, Bats, Rabbits, Weasels, Raccoons, Bears, Dogs, and Cats. Through the phenomenon of convergent evolution, similar-appearing structures may evolve in entirely un- related groups of organisms in quite different ways. Capsule material and yolk cells are deposited around each zygote, and the zygotes are moved into the uterus for temporary storage.

An Introduction to Nematodes: Plant Nematology (Pensoft

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Pp. 1-14, in: From DNA to diversity: molecular genetics and the evolution of animal design. Zool. 16: 277–291. [The introduction to an entire issue of American Zoologist (Spring 1976) devoted to an examination of those creatures showing spiral cleavage.] Dawydoff, C. 1928. This success is probably due, at least in part, to a compact body and reduced size. Gill slits may contain the gills and be used for gas exchange, as in most fish, but may also be used for filter-feeding, or may be highly modified in land-dwelling vertebrates. gnathobase -- The expanded and hardened base of the appendage of many arthropods, notably trilobites, crustaceans, and marine cheliceramorphs.

Marine Life of the Maldives

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A simple pharynx (or pharynx simplex) is a short, cil- iated tube connecting the mouth and intestine (Figure 10.12). Some are photo- synthetic, others are ingesting heterotrophs, and still 154 CHAPTER FIVE BOX 5I Characteristics of the Phylum Stramenopila 1. Accommodation during the conference will be in Tanta University, guest house. Makeup exams will generally be comprehensive oral examinations that are administered on the last day of the final exam period.

Biology of Free-living Nematodes

Warwick L. Nicholas

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Trichoplax has an outer, partly flagellated epithelium surrounding an inner mes- enchymal cell mass. You can also drag the edge of a column to make it wider or narrower. ) column to view the full record. Behind the esophagus is a long midgut leading to a short, cuti- cle-lined rectum and an anus located on an anal cone. These skeletons vary greatly in construction and ornamenta- tion, and frequently bear radiating spines that aid in flotation.

Physiological Approach to the Lower Animals

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They have strong jaws Cartilaginous Fish Continued… Their mouth is on the underside of their body. Here are a few search tips: Query results are limited to 4000 records. In order to take this course, you must: √ have access to a computer; √ have continuous broadband Internet access; √ have the ability/permission to install plug-ins (e.g. PHYLUM ANNELIDA 443UNCORRECTED PAGE PROOFS he coelomate worm phyla Sipuncula and Echiura are often dismissed in short fashion as “minor” or “lesser” groups.

Acarorum Catalogus: Acariformes, Acaridida,

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They said their findings in monarchs were consistent with previous studies comparing migratory and non-migratory bird species, which indicate the best shape for long-distance flight involves long wings with a narrow tip to help reduce drag. Other ciliates, including many of the more familiar forms (e.g., Stentor) are suspension feeders (Figure 5.18). They may help remove sediment particles and other material, but convincing evidence for this function is wanting. Fine structure patterns in crus- tacean rhabdomes.