Lecture 13 + 14 (BIO-2040)

shared features of arthopoda and annelida

1. arthropod-like cuticle

2. un-jointed legs

3. partial segmentation

Phylum Tarigrada

• survive almost anything

• external segmentation

• un-jointed legs with claws

Phylum Onychophora

soft chitinous/proteic cuticle

unjointed clawed legs

live in rain forests

Phylum sipuncula

very close to annelids (branched before metamism)

• deposit feeders

• have trochophore larva

Phylum Pogonophora

• live inside chitin tubes in the deep sea

• with tentacles but no digestive tubes

• Food comes from chemosynthesis (mutualism with bacteria)

“Lophoporates” shared characteristics

1. a lophophore

2. U-shaped digestive tracts

3. coelom divided into 3 pouches

the lophophore

• crown of hollow tentacles

• cilliated, covered by mucus

Phylum Phoronida

• sessile filter feeders

• look like cnidarian polyps

Phylum Branchiopoda

• lampshells

• dorsal and ventral valves

Phylum Bryozoa

• moss animals, for cononies

• all marine

• eperdermis secrets exoskeleton

Echinoderms

spiny skin animals

marine with penta radial symmetry

penta radial symmetry of echinoderms

secondary adaptation

1. ancestors were all bilateral

2. larve were all bilateral

Unique water vascular system of echinoderms

• the amburarcral system

• internal system with radial canals connected to out-pockets of body wall

• involved in multiple roles

madreporite

a dorsal plate with tiny canals that handle water pressure

Papulae

dermal gills of the coelom that help with excretion and gas exchange

• Most solids are expelled via the mouth, fine excretion is done by these

Pedicellaria

claw-like structures, keep surface clean for papillae

Radiation of Echinoderms

• starfish

• brittle stars

• sealillies

• sea cucumbers

• echinoids

Class Asteroidea

• a central disk surrounded by 5+ arms (with organs in them)

• ossicles of the endoskeleton protrude as blunt spines

• a keystone predator

Asteroidea movement

using podia or tube feet

Asteroidea feeding

• by double stomach (pyloric and cardiac)

• cardaic stomach emerges through the mouth to digest prey

Asteroidea Larvae

Bipinnaria & Brachiolaria

Asteroidea sexual reproduction

gonads located on each arm

Asteroidea asexual reproduction

be regeneration of arms, they do this often

Class Ophiuroidea

abundant

• slender arms around a central disk (no viceral organs)

• no anus

• tube feet for feeding

• madreporite is on one of 4-5 jaws

• scavengers

• short spines are located on the disk and arm

Ophiuroidea locomotion

flexible arms

Ophiuroidea sexual reproduction

adults spawn gametes, egg external fertilization

• hatch larvae and settle as juveniles

Ophiuroidea asexual reproduction

high respiration capacity: can regrow arms and part of central disk

Autotomy

the cut or release of body parts to escape predators

Class Echinoidea

• no arms, just a round disk

• about 2,000 species

• Grooves with podia remain visible

• red gonads on top, digestive glands below

• ossicles become large and fussed

Sea urchins

• spines are long and moveable (defence)

• high ecological and economic value

• live on hard substrates

• locomotion based on podia feet

Aritotle’s Laturn

jaw apparatus (chewing organs)

Sand Dollar

live in soft bottom

• flat with reduced movable spines

• deposit feeders (aristotles lantern also reduced)

• ecological but no commercial value

Echinoidea reproduction

• Mature ones produce eggs by external fertilization

• eggs hatch planktonic larvae (become juveniles)

Echinoidea Larvae

Echinopluteus

Class Holothuroidea

• about 1,000 species

• no arms

• oral-aboral axis lengthened

• developed tentacles around the mouth (for feeding)

• CaCO3 ossicles reduced, body is soft with thick dermis

Holothuroidea locomotion

fine grooves with tube feet are still visible

sea cucumber uses

• medical purposes

• of food with greens, rice, or spices

Holothuroidea sexual reproduction

• produce eggs, external fertilization

• hatch larvae, settle as juvenile

Holothuroidea larvae

Auriclaria

Class Crinoidea

• “leather” skin with plates

• mouth and anus face upward

• arms are dorsal and have tentacles

Crinoidea feeding

• filter feeders

• tentacles move the water and have mucus and help to trap food

Crinoidea larvae

Doliolaria

Crinoidea asexual reproduction

high regeneration capacity

Sea Lillies

• live in deep and shallow water

• have little commercial value

Phylum Hemichordata (weird cousin)

“Acorn Worms”

• marine from cambrian period

Hemichordata larva

Tornaria

• very similar to seastar larvae

Hemichordata Segmentation

body divided in probocis (collar and trunk)

Hemichordata respiration

• latter has gill/slits

• similar to chordates