The Lophophorate Phyla

EctoproctaBrachiopoda

Phoronida

By: Arnaiz, Martin Jr. A

three phyla share several distinctive characteristics:1. all possess a horseshoe-shaped or circular setof hollow ciliated tentacles for filter feeding

! = lophophore2. a “U-shaped” digestive system in which theanus opens OUTSIDE the lophophorealso3. nearly every member is sessile4. poorly developed head5. secretes a protective shell or flexible casing

Phylum Ectoprocta(bryozoa; moss animals)

Etymology:- From the Greek Bryon for moss and Zoon for animal. Etymology:- From the Greek Ektos for outside and Proktos for anus.

means “outside anus” an old name = “fairy lace”

The reference is to the anus located outside of the ring of ciliated tentacles (lophophores). The name was coined by (Nitsche 1869), but they are also known as Bryozoa (Ehrenberg 1831) and Polyzoa (Thompson 1830).

Fossil Record:~4500 living species; 16,000 fossils. rich fossil recordall are aquatic; marine or freshwaters especially in shallow waters.

The Bryozoa are the only animal phylum with an extensive fossil record that does not appear in Cambrian or late Precambrian rocks. The oldest known fossil bryozoans, including representatives of both major marine groups, the Stenolaemata (tubular bryozoans) and Gymnolaemata (boxlike bryozoans), appear in the Early Ordovician. It is plausible that the Bryozoa existed in the Cambrian but were soft-bodied or not preserved for some other reason; perhaps they evolved from a phoronid -like ancestor at about this time.

sessile; can be found on almost any hard surface:sea weeds, shells, rocks, even bottom of icebergs

almost all are colonialeach colony consists of individual zooids ~ .5mm long

colony may be >1 M long; most are smaller

colonies can be encrusting, arboreal or gelatinous balls

Body Formeach zooid lives in a tiny chamber that it secretes

= an exoskeleton->gelatinous, chitinous or hardened with calcium or sand

often with trapdoor = operculum tentacles (= lophophore) used for feeding and may play role in respiration

most zooids in most colonies are feeding zooidssome colonies contain other kinds of zooids:

a. zooids with “bird beaks”-protects colony from invaders

b. zooids with long bristles-sweep foreign material away from colony

Body Wallouter casing (exoskeleton) = zoecium made of chitin and calcium deposits

one area of the zoecium has a thinner flexible membrane embedded

interior of body with large coelom

coelom extends into lophophore

Feeding and Digestion

Digestive tract Gonads Retractor muscle Outer covering

ciliated tentacles draw water across to trap foodmouth is at center of lophophore

material trapped in tentacles is passed to mouth by ciliary movement and by pumping action of pharynx

from mouth food passes into a “U-shaped” digestive tract consisting of stomach which may have a gizzard and the intestine

waste material passes through intestine to anus (outside the ring of tentacles)

no respiratory or excretory organs or vascular system gasses are exchanged through body surface especially the tentacles

Reproduction: Asexual colonies produced by budding of a single larva which settles

and attaches to substrate freshwater forms also reproduce asexually by special resistant

bodies = statoblastsdisc shapedgerminative cells enclosed in tough capsulevery resistant to drying

statoblasts form during summer and fall in winter, colony dies, statoblasts remain

may fall to bottom or some float statoblasts remain dormant until spring or favorable conditions

appear then can regenerate a new colony

Reproduction: Sexual most are monoecious

-may have eggs and sperm produced simultaneously

most bryozoa brood their eggs externally or in body cavity

some shed eggs into water larvae of some show polyembryony

in which a single larva proliferates into several larvae

larvae swim for a few months before settling

Economic Importance:1. fossil bryozoa used extensively by petroleum companies as indicator fossils to find oil deposits2. over 17 antitumor chemicals have been extracted from various species3. since they grow on hard surfaces

-sometimes cause fouling of ship hulls and pilings4. pharmaceuticals

potent anticancer chemicals5. As fil ter feed ers, bry ozoans fil ter and re cir cu late water. It has been es ti mated that a colony of Zoobotryon ver ti cil la tum ap prox i mately 1 m^2 in size has the po ten tial to fil ter up to 48,600 gal lons of sea wa ter per year.

Phylum Brachiopoda(Lamp Shells)

The word "brachiopod" is formed from the Ancient Greek words βραχίων ("arm") and πούς ("foot"). They are often known as "lamp shells", since the curved shells of the class Terebratulida look rather like pottery oil-lamps

Fossil RecordThe bars indicate how many different kinds of brachiopod fossils that have been found by paleontologists during each time period.

335 living species; 30,000 fossilsfilter feeders with hard protective

shellsome resemble ancient roman lampmostly, sessile, bottom dwelling

animals (benthos)not colonial like other lophophoratesmost prefer shallow waters; a few

deeper formsmost live attached to rocks or firm

substrate

some (eg. Lingula) live in verticlal burrows in sandand mud bottoms

Lingula, the shell is about 3 cm long. (A) Dorsal view (B) the brachiopod at the top of its burrow attached to the bottom by a long pedicle

also an ancient group with extensive fossil record flourished in palaeozoic seaswere one of the dominant phyla after the Cambrian explosion

- had hard protective shell as the number of predators were increasing

most died out in great Permian extinctiononly 1% of species alive today

one genus, Lingula, alive today, dates back to Ordovician (450MY ago)-may be oldest “living fossil”

modern forms are usually 5 - 80 mm some fossils up to 30 cmmost live specimens are dull yellow or gray a few are orange or red

resemble bivalve molluscs -untill mid 1800’s was classified with them have calcareous shell and mantlebut resemblance is only superficial: >the two valves are dorsal/ventral>ventral valve is typically larger>promonant lophophore as feeding organ>most are attached to substrate by thick pedicel on ventral valve

Shell

shell is secreted by mantlethe smaller dorsal valve fits over larger ventral valvevalves may be ornamented with growth lines, fluting,ridges, spineshas hole for pedicelpedicel attaches animal to substrate is long, fluid filled muscular in some; not muscular in othersa few species have completely lost pedicel

Mantlesecretes shelloften bears long chitinous setaemay be for defense

Feeding and Digestionbrachiopods are filter feeders like otherlophophoratesMost of the body is in the posterior part of shell whilelophophore fills anteriortentacles of lophophore capture food collected by ciliary water currentsciliated groove brings food to mouth

ciliated groove brings food to mouthfeed on algae and organic detritus complete digestive tractamong lowest rates of metabolism of all animalscan survive long periods without oxygenminimal food requirements

Circulationcirculatory system with heart

some cells in “blood”; function uncertainmay be to move nutrients around

Excretionsystem of metanephridia

Nervous System and Sensesmost sensory receptors are on mantle margins

Reproduction and Developmentalmost all are dioecious

-produce temporary gonads

gametes discharged through nephridia

most fertilization is external

only a few species brood their eggs

direct development in some, free-swimming larvae in other species

eg. Lingulaeg. Terebratula

Phylum PhoronidaPhoronids, commonly called horseshoe worms, are sessile organisms that live exclusively in marine environments. They are attached to a substrate and live in a chitin-like tube that is made from secretions in their earlier stages of life.

These tubes eventually become decorated with debris and gives the horseshoe worm camouflage

a small group of 20 speciesworm-like animals2 mm up to 30cm; most <20 cm longall are marine benthic animals

inhabit shallow coastal watersmay be brightly colored: orange, pink, green, yellowall secrete a chitinous or leathery tube that is either buried in the sand or attached to rocks or shellsextend front end from tube to feeda few species bore into mollusc shells or calcareous rockgenerally solitary but some tend to aggregate making the seafloor

-resemble a flower bed

outer flexible cuticleepidermis secretes cuticlelayers of longitudinal and circular musclestrue coelom

Body Wall

Feeding & Digestionfilter feeders with conspicuous set of modified ciliated tentacles

= lophophorecircular or crescent shapedcoelom extends into tentaclesfeed on plankton and detrituscilia direct food toward mouthwith up to 50 ciliated tentacles in two spirals

-collects food-entangles it in mucous-cilia move it to mouth

typical U – shaped gut leads to anus outside lophophore

Respirationgas exchange through lophophore

Circulationclosed circulatory system with hemoglobin inside blood cells

-adaptation to life in anoxic or low O2 environmentsno heart, some vessels constrict to pump blood

Excretionpaired metanephridia for excretion

Nervous Systemsimple diffuse nervous system with nerve ring but no distinct brain

Reproduction and Developmentmost are hermaphrodites; some are dioecious

-but usually cross fertilizefertilization can be internal or externaleggs fertilized internally are released through nephridioporein some tentacles brood eggsfree-swimming ciliated larva metamorphoses into

sessile adultat least two species reproduce asexually

END