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Invertebrates

Biology of the Invertebrates, Fourth Edition

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The chemical integrating system in animals that lack a vertebral (spinal) column. In addition to giving rise to other structures (such as the muscles of the gut and body wall), in coelomate animals mesoderm is intimately associated with the for- mation of the body cavity. Some scientists try to divide up living items because they say they all have 1 ancestor. Metazoan Roots We touched on the origin of the Metazoa in Chapters 1 and 4. When female mammals ovulate, the egg, if fertilized, is retained within the uterus. papilla(e) -- Cellular outgrowths.

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Invertebrates

Annotated Catalogue of African Grasshoppers 2-Part Set:

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PHYLUM GASTROTRICHA ORDER MACRODASYIDA: (Figure 12.9C–F). Various immunological assays revealed presence of special proteins in different vertebrates. Molecular Phylogenetics and Evolution 24:345-357. Note the confluent coelomic cavities. (C) A motile colony of Cristatella mucedo crawling over a plant stem. (D) A colony of Eurystomella. (E) A colony of the freshwater ectoproct Cristatella. (D) (E) UNCORRECTED PAGE PROOFS In addition to variation in overall form of the colonies, zooids of many gymnolaemates and some stenolaemates are polymorphic (within a colony).

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Invertebrates

Zoology

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Fine structure of a poten- tial photoreceptor organ in the larva of Bugula neritina (Bryozoa). A single anterior tooth projects down below the second hook on the left side of the photo, and two posterior teeth can be seen between the first and second hooks. A coeloblastula forms and gastrulates by invagination. This diagram illustrates the formation of a food vacuole, the fusion of a lyso- some from the Golgi body and the food vacuole, and the remaining digestive vacuole that will carry wastes back to the cell surface. (B) Pinocytosis.

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Invertebrates

A Guide to Common Freshwater Invertebrates of North America

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The gonads arise on the walls of the meridional canals (Figure 9.8). The Chengjiang fauna is very similar to that of the Burgess Shale, and it demonstrates that the arthropods were already far advanced by this early date. The researchers subsequently found that hungry animals in flowing seawater could be induced to feed at any time by simply adding cultured phytoplankton to the tank water (Rabindra et al. 1998). For example, the coral-inhabiting sponge Siphonodictyon releases a toxic chemical into the mucus exuded from its oscula, thus preventing potential crowding by maintaining a zone of dead coral polyps around each osculum (Figure 6.17).

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Invertebrates

EXPLORING PARASITE GENOMES SYMPOSIA OF THE BRITISH SOCIETY

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The sea daisy Xyloplax medusiformis lacks a digestive system, but the oral surface is covered by a membra- nous velum that may have been derived from the gut (Baker et al. 1986). Engulfment of Prochloron cells by cells of the ascidean, Lissoclinum. Gastropods may be dioecious or hermaphroditic, but even in the latter case only a single gonad (an ovotestis) exists. These tiny flatworms feed on protozoa and bacteria, and some may devour cells of their hosts.

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Invertebrates

PARASITE ADAPTATION TO ENVIRONMENTAL CONSTRAINTS -

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White, “The anatomy,” in The Nematode Caenorhabditis elegans, W. The phenomenon of industrial melanism in Lepidoptera. These flosculi may be tactile or chemosensory. Chrysomelidae-Cassidinae is the finest collection of tortoise beetles in the world. All hydrozoan cnidarians have a sexual phase in their life cycle (Figure 8.37). Charles Walcott) shows a sea star that lost an arm and is in the process of regenerating a replacement. They extract food particles, mostly phytoplankton, from currents pro- duced by the lateral cilia on the tentacles (Figure 12.32B).

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Invertebrates

A Monograph of the Fresh-Water Polyzoa, Including all the

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Such animals are said to have indeterminate cleavage. As new characters or new species are identi- fied and their character states elucidated, new data ma- trices are developed, and new analyses are undertaken. The adductor muscles in- clude both striated and smooth fibers such that the valves can be quickly closed and then held together for long pe- riods of time. However, the molluscan nervous sys- tem differs from that of annelids and arthropods, in which the ventral nerve cord(s) bears segmentally arranged ganglia.

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Invertebrates

C. Elegans Atlas

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Gas exchange currents carry particulate matter into the mantle cavity. Some work- ers have held to the view that the infusoriform larva en- FOUR PHYLA OF UNCERTAIN AFFINITY 213 Figure 7.3 Sexual reproduction in dicyemid rhombo- zoans. (A) Sexual (rhombogen) form of vermiform adult. (B) Infusorigen of sperm and ova formed within the axial cell of the vermiform adult. (C) Infusoriform larva pro- duced by fertilization. (D) Stem nematogen with three axial cells. Fertilization is usually external, except in Phoronopsis harmeri and LOPHOPHORATES 7UNCORRECTED PAGE PROOFS Figure 21.3 (A) A phoronid metanephridium (from Phoronis australis).

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Invertebrates

Molecular and Physiological Basis of Nematode Survival

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The phylum Loricifera was established in 1983 by Reinhardt Kris- tensen, and the phylum Cycliophora was described in 1995 by Peter Funch and R. The liquid flows along a groove in the foot to the substratum, where each thread becomes tightly affixed. This collection complements the Division’s holdings gathered by A. Fertilization takes place as the eggs are laid. Molecular studies are expected to lead to additional rearrangements. A class of asexual rotifers called Bdelloidea consists of 360 species that all reproduce by parthenogenesis without males.

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Invertebrates

Identification Keys to the Microlepidoptera of the

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Marine turbellarians are often the most colorful and graceful creatures found in tide- pools. Hence, prolegs may have reap- peared in groups such as the Lepidoptera through some- thing as simple as the de-repression of an ancestral limb development program (i.e., they are a Hox gene–medi- ated atavism). There are several jars containing multiple specimens in the Museum, and there are a number of reasons why they might be prepared like this. The females store sperm in the spermatheca, in some cases holding enough sperm from a single mating to last a lifetime.

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