Sawfishes are a group of extremely large shark-like rays which haunt the muddy shallows of tropical bays, rivers and lakes. Though fearsome in appearance, sawfishes are very docile. Due to decades of incidental capture in nets set for other species, sawfishes are in serious trouble and populations worldwide are severely depleted... ORIGIN & EVOLUTION Sharks arose from a common ancestor to bony fishes over 400 million years ago (mya) during the Silurian period. Cartilaginous fishes went a different direction in solving issues of buoyancy, physiology, and locomotion. In the Late Jurassic period, approximately 163 mya, a major break occured within the shark line when certain sharks began to exploit a new niche, taking advantage of rich food sources on the sea floor. As these specialist sharks spent more time at the bottom, their bodies flattened, facilitating their feeding and resting on the substrate. This group became the rays, also known as batoids. The first true rays looked much like modern guitarfishes, with a shark-like body and pointed, flattened head. True sawfishes, the family Pristidae, first trolled the murky margins of warm Eocene seas only 56 mya, evolving directly from an unidentified Paleocene guitarfish species. This family is characterized by the implantation of continuously growing rostral teeth into sockets on the edge of the saw. Roughly 40 species of modern sawfishes have been identified; only a handful survive today. Sawfishes appear very shark-like because they branched off from the rays very early, before more modified ray body types emerged such as stingrays or eagle rays. ANATOMY When we look at a sawfish, we can tell about its lifestyle from its body form. Its shark-like tail propels it through the water with graceful undulations. The tail shape reveals that sawfishes are slow swimmers. A flattened body and head indicate a fish that lives on the bottom. Behind each eye are openings called spiracles, often mistaken for ears. Spiracles are used by rays to inhale water when they rest on the bottom. The eyes are set on top of the head so they can see when partially buried. While sawfishes have decent eyesight, their habitat is so murky that vision is not very useful. The remarkable snout, however, houses two sophisticated sensory systems, allowing sawfishes to feel the movements of distant animals, and even sense the heartbeats of buried prey. The toothy snout is usually between 1/4 and 1/5 of the sawfish's total length. The sharp awl-like teeth are not true teeth at all; they are really modified scales, which enlarged over time and became embedded deep inside the rostrum. As with other rays, the mouth, nares (nostrils), & gill slits are located on the flat undersurface. The jaws are lined with a pavement of thousands of tiny dome-shaped teeth. Sawfishes eat only small fish and bottom-dwelling invertebrates, like crabs and shrimps, which can be crushed and swallowed whole through the mouth. The skin is covered by a protective layer of enameled scales called dermal denticles (literally, 'little-skin-teeth'). Teeth in sharks and rays evolved from these rough tooth-like scales. Like most elasmobranchs, sawfishes are countershaded. The upper surface is dark to blend in with the substrate; the underside is white, to blend in with the surface when seen from below. Sawfishes range in color from light grey, to beige, to brown, and even olive green. Like other elasmobranchs (sharks and rays), the sawfish has a cartilaginous skeleton and no swim bladder. Instead, elasmobranchs rely on a huge yellow, oil-filled liver to give them buoyancy. When sawfishes eat, the food passes from the stomach into a corkscrew-shaped intestine called the spiral-valve. Male sawfishes mate using a pair of rod-like organs near their pelvic fins called claspers. LIFE HISTORY Sawfishes are very lethargic animals, spending much of their day nestled in the muddy sea/river floor. At night, they scull slowly through the shallows, using their sensitive saw to find buried prey, which are then raked from the sediment to be consumed. It is useful to view the sawfishes' unique rostrum like a metal detector combined with a clam rake. If small fishes, like mullet, swim past a hungry sawfish, this great ray will launch from the bottom, slashing its toothy weapon rapidly side to side. Gouged by the snout's awl-shaped teeth, injured fishes tumble to the sea floor, now immobilized and easy to catch. Apart from its use in finding and disabling prey, the toothy rostrum is also a weapon of defense. When threatened, sawfishes will smack this jagged sword against attackers, whether they be sharks or fishermen. Generally, though, sawfishes are very gentle animals, prefering to lie quietly, undisturbed. Very little is known about sawfish life history, but the late Dr. Thomas Thorson performed studies on a freshwater species, the Largetooth sawfish ( Pristis perotteti ) from Lake Nicaragua. According to hi

The Nave, notably tall and narrow, with side walls 0.88 - 0.91 m in thickness, is of four bays; as both fabric and features of the nave walls are so crucial to the interpretation of the structural history of the church, they are described in some detail here, the arcades first, and then the fabric and features of the walls above. The arcades are in two sections, a three-bay east part, then, beyond a short block of solid walling, a western pair of arches. The three-bay parts have semicircular arches of two chamfered orders, with hoodmoulds towards the nave, and are carried on circular piers and responds with full-height keeled half-shafts (except for the eastern of the south arcade, which has its half shaft carried by a bracket with stiff-leaf foliage). The capitals, all somewhat mutilated, are ornamented with stylised leaf forms, all differing, and rather more developed on the north; the western capital of the north arcade is the best-preserved, and has well-developed volute-like foliage. The bases, some very much mutilated, all seem to have had hold water mouldings; those of the piers have been set on circular plinths, although that of the eastern pier of the south arcade has had a square extension to the south made when a respond (removed in 1849) was added, in connection with the 13th- century addition of a south transept. Hodgson claimed to have found ‘unmistakable fragments of interlaced Saxon knot-work... worked into the foundation of the easternmost 12th-century pier on the south side of the nave’ (1889. 75, footnote 2) but no trace of these can now be found. The hoodmould of the south arcade has an indented ornament (sometimes termed ‘nutmeg’) seen again at St Helen Auckland. The hoodmould of the north arcade has been cut away at the east end (presumably to accommodate the rood beam); above the second pier it has a stop in the form of a stylised human head, possibly wearing a gag. The western arch of each arcade is of a rather awkward stilted semicircular shape, due to the fact that whilst the eastern respond is at the same level as those of the main part of the arcade, the western, at the level of those of the tower arches, is set considerably. The arches themselves are again of two chamfered orders, the outer order ending in broach stops above the western respond only; there is a hoodmould chamfered on its lower angle; the responds have filleted half shafts, very like those of the tower arches. Whilst the three-bay arcades seem to have been untouched (except perhaps for a superficial tooling-over) by 19th century restoration, these western arches look rather more suspicious. The dressings of the eastern third of each arch seem in better condition than the remainder, and, especially on the south, are lighter in colour. The mouldings of the respond capitals also seem in suspiciously good condition, although the mutilated bases look. The walls above the arcades are of coursed roughly-squared stone, although a number of changes are visible. On both internal and external wall faces show added clerestory walling is plainly distinguishable. In the spandrels above the easternmost pier of each arcade are the remains of an earlier window, discovered and partially opened out in the 19th century. That on the south is the more intact; the rear arch shows a series of neatly-cut splayed voussoirs, the curve of the extrados following that of the arch; the splay of the head retains old white plaster. The outer opening, which has the narrowest of chamfers, has its semicircular head cut into a single elongate block of whitish stone; a single block that survives from the upper part of the east jamb. Less survives of the northern window; four curved blocks of the rear arch are visible and only the head of the outer opening. Both internal faces of the nave walls show, below the added clerestory, a clear vertical break above the elongate ‘pier’ between the third and fourth arches of the arcades, which has been interpreted as indicating the position of the west wall of the earliest nave. However, the fabric and features hereabouts are not at all easy to interpret in detail. On the south, the break aligns more or less with the respond of the main part of the arcade, and has a series of large quoin like blocks set against it. To the west of these is a wedge-shaped area of rather larger stonework, notably lighter in colour, before darker rather more thinly-coursed stonework, very like that above the main part of the arcade, resumes. It is interesting that this lighter-coloured stonework corresponds in position with the lighter-coloured and more recent-looking dressings of the eastern third of the fourth-bay arch directly below. On the external face of the wall matters are less clear. The head of the pre-clerestory walling is marked by a slight set-back, accompanied by a linear feature which may be what Taylor & Taylor (1965, 265) describe as a ‘hollow-moulded string course’ but in fact looks much more like a timber