The ecological tradition is different: ecologists emphasise the diversity of their organisms, and many ecologists would argue that their organism is ‘unique’ because it exhibits adaptations to its environment. This uniqueness is encapsulated in the Linnaean binomial nomenclature: this label, by definition, establishes that a group of organisms is distinct enough from their relatives. Sticking t...

The medicinal leech is a useful animal model for investigating undulatory swimming in the classroom. Unlike many swimming organisms, its swimming performance can be quantified without specialized equipment. A large blood meal alters swimming behavior in a way that can be used to generate a discussion of the hydrodynamics of swimming, muscle mechanics, hydrostatic skeletons, and the physiologica...

INTRODUCTION.................................................................. 442 FINE STRUCTURE OF FLAGELLA.................................................. 443 Comparative Anatomy of the Flagella of Bacteria and Other Organisms ......... 443 Chemical and Physical Properties of Bacterial Flagella........................ 444 Electron Microscope and X-Ray Diffraction Studies of Bacterial Flage...

1. Repeating bursts of motor neurone impulses have been recorded from the nerves of completely isolated nerve cords of the medicinal leech. The salient features of this burst rhythm are similar to those obtained in the semi-intact preparation during swimming. Hence the basic swimming rhythm is generated by a central oscillator. 2. Quantitative comparisons between the impulse patterns obtained f...

The study of non-model organisms stands to benefit greatly from genetic and genomic data. For a better understanding of the molecular mechanisms driving neuronal development, and to characterize the entire leech Hirudo medicinalis central nervous system (CNS) transcriptome we combined Trinity for de-novo assembly and Illumina HiSeq2000 for RNA-Seq. We present a set of 73,493 de-novo assembled t...

In leech visual cells the presumed light-absorbing structures are microvilli arising from the membrane of what would seem to be a large intracellular vacuole. This vacuole, however, is an extracellular compartment, since it communicates with the intercellular spaces through narrow channels. Therefore, the membrane of the microvilli is-as in other invertebrate visual cells-a part of the cell mem...

Semi-intact tethered preparations were used to characterize neuronal activity patterns in midbody ganglia of the medicinal leech during crawling. Extra- and intracellular recordings were obtained from identified interneurons and from motor neurons of the longitudinal and circular muscles during crawling episodes. Coordinated activities of nine excitatory and inhibitory motor neurons of the long...

Swimming and the whole-body shortening reflex are two incompatible behaviors performed by the medicinal leech Hirudo medicinalis. We set out to examine the neuronal basis of the choice between these behaviors, taking advantage of the fact that the neuronal circuit underlying swimming is relatively well understood. The leech swim circuit is organized hierarchically and contains three interneuron...