scallops Zebra Mussel ctenidium

Size: px

Start display at page:

Download "scallops Zebra Mussel ctenidium"

Myles Oliver
5 years ago
Views:

1 7650 species Mostly marine About one thousand species live in fresh water clams scallops Zebra Mussel mussels oysters Zebras on native clams (Unionidae) ctenidium Right valve umbo Adductor muscle Best understood in the context of their largely sedentary adult life style Labial palps mouth Foot Mantle edge Excurrent Incurrent siphons Two principal types, distinguished by their Ctenidia and mode of feeding Ctenidia of Bivalves are modified for feeding except in one group: the Protobranchs Class Bivalvia Protobranchia Llamellibranchia 1

In most bivalves ctenidia are sheet-like with high S.A.

ventral groove and then as a mucus strand to the mouth. http://www.

page=252 Summary of Water Flow and Feeding http://web.uconn.

mpg Mussel lamellibranch (filibranch) ctenidium Feeding simulation

ca/facilities/multimedia/uploads/zoology/filibranchbivalve.

as the Llamellibranch condition Living Cephalopods Nautilus Squid

Colossal squid up to 14 m major prey item of sperm whales Octopods

2 In most bivalves ctenidia are sheet-like with high S.A., and are used for feeding Captured particles are moved to a ciliated ventral groove and then as a mucus strand to the mouth. Summary of Water Flow and Feeding Mussel lamellibranch (filibranch) ctenidium Feeding simulation The sheetlike, arrangement of ctenidia in most bivalves is known as the Llamellibranch condition Living Cephalopods Nautilus Squid Architeuthys Giant squid up to 20 m long Cuttlefish Mesonycheteuthis Colossal squid up to 14 m major prey item of sperm whales Octopods --The class as a whole is adapted for swimming, suspended in the water by buoyancy mechanisms. Dosidicus Humboldt squid, smaller but numerous (2 m) and comes to surface to feed -- all are carnivores, occupying the same niche as fishes 2

3 Ammonites Sub Class Nautiloidea 5-6 species remain from diversity in geologic past Live in the last chamber of a multi-chambered shell Largest is 3 m in diameter Move by forcing water through a siphon. Sub Class Nautiloidea How does a Nautilus adjust and maintain its buoyancy in water? Cuttles, Squids and Octopuses - tendency is reduction of shell. - compensated for by selective ionic control; accumulate ammonium - other adaptations to shell loss and life style cuttle Specifically, compensation takes the following forms: chameleons of the sea Stealth and other defenses Acute sensory structures Speed Cunning octopus most specialized, agile and cryptic 3

Figure 2. A) Chromatophores on skin of Loligo. (CephBase image No. 280 by Roger T. Hanlon) B) Chromatophores visible on Lolliguncula brevis (CephBase image No.

Stealth and other defenses Chromatophores: each cell contains a different pigment which may be red, orange, brown, black, yellow or blue Ink Sack : ink with

Messenger 1996). These cells are located directly under the skin of cephalopods.

When the muscles relax, the saccule shrinks and hides the pigment.

In some squid, each chromatophor muscle is innervated by 2 to 6 nerves that directly link to the animals brain (Messenger et al 2001).

This allows the cephalopods to produce complex patterns (Messenger 2001, Messenger et al 2001), such as the zebra stripes seen in aggressive displays by male

In some species of cuttlefish, it has been noted that while hunting, the cuttlefish may produce a series of stripes that move down their bodies and arms.

The pigments in chromatophores can be black, brown, red, orange or yellow.

Interestingly, many deep water forms possess fewer chromatophores as they are less useful in an environment in little or no light.

com Iridophores are found in the next layer under the chromatopphores (Hanlon et al 1990, Cooper et al 1990).

They are responsible for producing the metallic looking greens, blues and golds seen in some species, as well as the silver color around the eyes and ink sac

4 Figure 2. A) Chromatophores on skin of Loligo. (CephBase image No. 280 by Roger T. Hanlon) B) Chromatophores visible on Lolliguncula brevis (CephBase image No. 263 from UTMB). A. Stealth and other defenses A. Stealth and other defenses Chromatophores: each cell contains a different pigment which may be red, orange, brown, black, yellow or blue Ink Sack : ink with melanin and mucus also dopamine, L-DOPA, tyrosinase Pseudomorphs Cephalopod Chromatophore Cephalopod Skin Papillae 9/16/ :42 AM The most well known of these cells is the chromatophore. Chromatophores are groups of cells that include an elastic saccule that holds a pigment, as well as muscles attached to this saccule (Hanlon and Messenger 1996). These cells are located directly under the skin of cephalopods. When the muscles contract, they stretch the saccule allowing the pigment inside to cover a larger surface area. When the muscles relax, the saccule shrinks and hides the pigment. Unlike other animals, the chromatophores in cephalopods are neurally controlled, with each chromatophore being attached to a nerve ending (Messenger 2001). In some squid, each chromatophor muscle is innervated by 2 to 6 nerves that directly link to the animals brain (Messenger et al 2001). In this way the animal can increase the size of one saccule while decreasing the size of another one right next to it. This allows the cephalopods to produce complex patterns (Messenger 2001, Messenger et al 2001), such as the zebra stripes seen in aggressive displays by male cuttlefish. The speed at which this can be controlled allows the animal to manipulate these patterns in a way that makes them appear to move across the body. In some species of cuttlefish, it has been noted that while hunting, the cuttlefish may produce a series of stripes that move down their bodies and arms. Some scientists have suggested that this could be used to mesmerize prey before striking, but the purpose of this behavior has yet to be proven. The pigments in chromatophores can be black, brown, red, orange or yellow. They are not responsible for producing the blue and green colors seen in some species. Interestingly, many deep water forms possess fewer chromatophores as they are less useful in an environment in little or no light. Black, brown, orange or yellow colors Also iridiophore reflective cells Most cephalopods are completely colorblind neurophilosophy.files.wordpress.com Iridophores are found in the next layer under the chromatopphores (Hanlon et al 1990, Cooper et al 1990). Iridophores are layered stacks of platelets that are chitinous in some species and protein based in others. They are responsible for producing the metallic looking greens, blues and golds seen in some species, as well as the silver color around the eyes and ink sac of others (Hanlon and Messenger 1996). Iridophores work by reflecting light and can be used to conceal organs, as is often the case with the silver coloration around the eyes and ink sacs. Additonally they assist in concealment and communication. Previously, it was thought that these colors were permanent and unchanging unlike the colors produced by chromatophores. New studies on some species of squid suggest that the colors may change in response to changing levels of certain hormones (Hanlon et al 1990, Cooper et al 1990). However, these changes are obviously slower than neurally controlled chromatophore changes. Iridophores can be found in cuttlefish, some squid and some species of octopus. B. Acute sensory structures -- Vision -- Lateral line analogs C. Speed Rival fish in ability to swim, attaining burst speeds of 5-10 m second sustained for short distances at speeds of up to 40 km hr. Burst speed is achieved by jet propulsion More gradual swimming is fin undulation 4

C. Speed : complex nerve control of locomotion C.

contraction of mantle muscles Hearts Requires a closed,

Cunning Experiments with Octopus vulgaris show their

They learn to choose colors not associated with shock.

5 C. Speed : complex nerve control of locomotion C. Speed : circulatory system Assures synchronized contraction of mantle muscles Hearts Requires a closed, elaborate circulatory system D. Cunning Experiments with Octopus vulgaris show their ability to learn. They learn to choose colors not associated with shock. -- Relative to body size, the brain is larger than that of most fish Observers choose properly colored objects after watching demonstrators 5

Bivalved molluscs filter feeders

Bivalved molluscs filter feeders Class Bivalvia Bivalved molluscs have two shells (valves). Mussels, clams, oysters, scallops, shipworms. Mostly sessile filter feeders. No head or radula. Class Bivalvia Part of the mantle is modified