phylum echinodermata “spiny skin” over 6000 marine species

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Phylum Echinodermata “spiny skin” Over 6000 marine species

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Page 1: Phylum Echinodermata “spiny skin” Over 6000 marine species

Phylum Echinodermata

“spiny skin”

Over 6000 marine species

Page 2: Phylum Echinodermata “spiny skin” Over 6000 marine species

Phylum Echinoderms

• Echinodermata are all marine, triploblastic unsegmented coelomates

• Phylum has 3 unique features:– pentagonal symmetry (bilateral in larvae)

–Tube feet (podia)

–calcite spicules embedded in the skin, often partly fused

Page 3: Phylum Echinodermata “spiny skin” Over 6000 marine species

Things they share

• Symmetry– Adults with pentaradial symmetry

Round body with body parts radiating from center

Page 4: Phylum Echinodermata “spiny skin” Over 6000 marine species

Water vascular system

• Locomotion

• Attachment• Feeding

Page 5: Phylum Echinodermata “spiny skin” Over 6000 marine species

Water vascular system• Complex system of water filled canals

• Extensions of tubed feet

•Modification of the coelom

•Ciliated internally

Page 6: Phylum Echinodermata “spiny skin” Over 6000 marine species

Figure 16.4

Ring canals associated with each arm Lateral canals end at each tube feet

Madreporite serve to replace water lost from the WVS and equalize pressure

Page 7: Phylum Echinodermata “spiny skin” Over 6000 marine species

Water Vascular system con’t

• Ring canal that surrounds the mouth

• Ring canal opens to the outside or body cavity through a stone canal and an opening called a Madreporite

Page 8: Phylum Echinodermata “spiny skin” Over 6000 marine species

Tube feet

• Usually emerge through openings in skeletal ossicles

• Extensions of the canal system

Page 9: Phylum Echinodermata “spiny skin” Over 6000 marine species

Figure 16.5

Suction cups

Page 10: Phylum Echinodermata “spiny skin” Over 6000 marine species

Figure 16.6

Oral opening- or mouth normally faced downward with moveable oral spines around it

Page 11: Phylum Echinodermata “spiny skin” Over 6000 marine species

Tube feet

• Also permit exchange of respiratory gases and nitrogenous waste

• Sensory functions

Page 12: Phylum Echinodermata “spiny skin” Over 6000 marine species

Nervous system

• Echinoderms have a diffuse nervous system with no “brain”

• Nerve ring that encircles the mouth

• Radial nerves that extend to each arm

• Coordinate the functions of tube feet

• Nerve net that coordinates the function of the body wall

Page 13: Phylum Echinodermata “spiny skin” Over 6000 marine species
Page 14: Phylum Echinodermata “spiny skin” Over 6000 marine species

Hydraulics

• These are far more complex than the nervous system!

• Main hydraulic systems are derived from the coelom, although separate sections of the coelom also surround viscera

• The podia are operated by a hydraulic system called the water-vascular system

Page 15: Phylum Echinodermata “spiny skin” Over 6000 marine species

Class Asteroidea

• Sea stars

Some live in sandy or muddy substrates

Page 16: Phylum Echinodermata “spiny skin” Over 6000 marine species

Sea StarVarious colors

•Usually five arms that radiate from a central disk

1,500 species

Live on hard substrates

Page 17: Phylum Echinodermata “spiny skin” Over 6000 marine species

Exception to the rule

• Some sea stars that have 6 or 7 arms

OR MORE!

Page 18: Phylum Echinodermata “spiny skin” Over 6000 marine species

Figure 16.7Development of a sea star

Page 19: Phylum Echinodermata “spiny skin” Over 6000 marine species

Regeneration• Arm

• An entire sea star?

Page 20: Phylum Echinodermata “spiny skin” Over 6000 marine species

Madreporite• Is stated to allow pressure

equalization and top up water supply to the WVS

• There is something of a mystery here - the madreporite shows a continual water influx, but animals in which it is experimentally blocked appear to function and move normally

• Is absent in crinoids

Page 21: Phylum Echinodermata “spiny skin” Over 6000 marine species

Gonads

• Sexes are separate, and discharge gametes into the sea water in response to chemo-stimulus of other gametes.

• There are gonopores, ie 2 per arm in asteroidea at the base of ambulacral grooves.

• Gonads can be large - echinoid gonads almost fill the test, and can be eaten as a delicacy.

Page 22: Phylum Echinodermata “spiny skin” Over 6000 marine species

Figure 16.8Sea daises

Page 23: Phylum Echinodermata “spiny skin” Over 6000 marine species

Class Crinoidea

• Crinoids or feather stars - almost certainly close to the ancestral form of the phylum

• These are mainly abyssal filter feeders, though in previous geological periods were dominant in shallow waters

• Some Carboniferous fossil beds are made of crinoid ossicles

Page 24: Phylum Echinodermata “spiny skin” Over 6000 marine species

Crinoidea

• Body is mainly made of ossicles

• 10 arms have podia (no ampullae) lining ciliated grooves feeding particles to the mouth. Podia seem to catch large particles

• Arms can move, thanks to muscles between arm ossicles

• Mouth and anus are both on oral side (!)

Page 25: Phylum Echinodermata “spiny skin” Over 6000 marine species

Figure 16.15

Class Crinoidea

Sea lily

Page 26: Phylum Echinodermata “spiny skin” Over 6000 marine species

Figure 16.16

Class CrinoideaFeather Star

Page 27: Phylum Echinodermata “spiny skin” Over 6000 marine species

Comatulids

• Free living crinoids - “feather stars”

• Have >10 arms, often migrating vertically to filter feed in shallow waters at night, usually by crawling

• Antedon: A. bifida is found in UK waters. This can swim actively.

Page 28: Phylum Echinodermata “spiny skin” Over 6000 marine species

Figure 16.12

•The mouthparts are unique, 5-radiate (of course!), known as Aristotle’s Lantern. This involves 5 continually growing chisel teeth, each with 8 supporting skeletal pieces. This gives the teeth remarkable versatility in their action.

Page 29: Phylum Echinodermata “spiny skin” Over 6000 marine species

Class Echinoidea- Sea Urchin•Are all herbivores, preferring macro-algae so are mainly found in sunlit waters.

•They can be highly effective grazers, creating “urchin barrens” devoid of algae

Page 30: Phylum Echinodermata “spiny skin” Over 6000 marine species

Figure 16.11 (a)

Page 31: Phylum Echinodermata “spiny skin” Over 6000 marine species

Sea Urchin test

Page 32: Phylum Echinodermata “spiny skin” Over 6000 marine species

Figure 16.11 (b)

Page 33: Phylum Echinodermata “spiny skin” Over 6000 marine species

Sand dollar and Sand biscuit

Page 34: Phylum Echinodermata “spiny skin” Over 6000 marine species

Ophiuridae - brittle stars

• These resemble bony starfish in general appearance, but have arms sharply demarcated from the body disc.

• The internal structure of the arms involves interlocking internal ossicles, confusingly called vertebrae.

Page 35: Phylum Echinodermata “spiny skin” Over 6000 marine species

• .. Are primarily detrital or filter feeders, raising their arms in a current to capture particulates

Page 36: Phylum Echinodermata “spiny skin” Over 6000 marine species

Figure 16.9 (a)

Page 37: Phylum Echinodermata “spiny skin” Over 6000 marine species

Holothuridae- Sea Cucumbers

• No Arms• Elongate along oral-aboral axis• Lie on flatten ventral side• They have no calcitic skeleton, except for spicules

embedded in a leathery skin• Most are immobile, and lie on the sea bed rolling back

and forth with the swell. Some have limited mobility using their tube feet.

• Despite retaining 5-radiate anatomy, they have re-evolved bilateral symmetry along their long axis (the oral-aboral)

Page 38: Phylum Echinodermata “spiny skin” Over 6000 marine species

Holothuridae• They have 2 odd defensive strategies:

– Squirting a stick goo from cuverian glands.

– Voiding their entire intestines. …yummy

Page 39: Phylum Echinodermata “spiny skin” Over 6000 marine species

•They mainly feed on detritus, collected by oral tentacles which are derived from tube feet.

Oxygen exchange is performed using gills inside their anusHmm…

Page 40: Phylum Echinodermata “spiny skin” Over 6000 marine species

Figure 16.13

Page 41: Phylum Echinodermata “spiny skin” Over 6000 marine species

holothuroidea

• Sea cucumber Sea apple