The Oyster card is a form of electronic ticket used on public transport in Greater London in the United Kingdom.
It is promoted by Transport for London and is valid on travel modes across London including London Underground, London Buses, the Docklands Light Railway (DLR), London Overground, Tramlink, some river boat services, and most National Rail services within the London fare zones.
There are only about 600 extant crinoid species, Crinoids comprise three basic sections; the stem, the calyx, and the arms.
The stem is composed of highly porous ossicles which are connected by ligamentary tissue.
Sponges do not have nervous, digestive or circulatory systems.
Instead, most rely on maintaining a constant water flow through their bodies to obtain food and oxygen and to remove wastes.
They are multicellular parazoan organisms that have bodies full of pores and channels allowing water to circulate through them, consisting of jelly-like mesohyl sandwiched between two thin layers of cells.
Sponges have unspecialized cells that can transform into other types and that often migrate between the main cell layers and the mesohyl in the process.Although the basic echinoderm pattern of fivefold symmetry can be recognised, most crinoids have many more than five arms.Crinoids usually have a stem used to attach themselves to a substrate, but many live attached only as juveniles and become free-swimming as adults.The majority of living crinoids are free-swimming and have only a vestigial stalk.In those deep-sea species that still retain a stalk, it may reach up to 1 metre (3.3 ft) in length, although it is usually much smaller.The Oyster card was set up under a Private Finance Initiative (PFI) contract between Transport for London (Tf L) and Tran Sys, a consortium of suppliers that included EDS and Cubic Transportation Systems (responsible for day-to-day management) and Fujitsu and WS Atkins (shareholders with no active involvement).