Lab 10: Introduction to Deuterostomes Flashcards
What two phylum are in the deuterostomes?
- Echinodermata
2. Chordata
What characterizes deuterostomes?
they are named for one of their shared derived characters *(called synapomorphies) of having the second opening of the blastopore become the mouth and opposed to protostomes
- other synapomorphies include: radial cleavage with indeterminate cells (can develop into any body part)
- enterocoelic formation (coelom forms from out pockets of the gut in the blastopore stage)
What are the basic features of Echinodermata and what species do they include
- group of marine invertebrates like: sea stars, sea urchins, sand dollars, sea cucumbers, brittle stars and sea lilies
- have a five part radial symmetry as adults and calcareous endoskeleton (made of calcium-carbonate -> chalky)
- Have small plates that are spiny
- the embryos are bilaterally symmetric like chordate embryos (secondary radial symmetry formed –> they were initially bilateral but then because of their sedentary movements they turned into radial again)
- sea cucumbers are the only bilaterally symmetrical species
- feed by water vascular system which first evolved for feeding, but as they became motile, it became for locomotion as well (moves in a all directions).
- Suction cup at the bottom of them called tube feet release and de-reelease by drawing in water and becoming adhesive to certain surface or non-adhesive in others
How are sea star species vital to the structure of intertidal and deep sea ecosystems?
they act as keystone predators that keep populations of small organisms like sea urchins and mussels in check
- if they weren’t present, it would threaten the biodiversity of the ecosystem
- the crown-of-thorns sea star in northern australia is damaging the ecosystem by destroying coral cover in the area
Which 4 structures do chordates display at some point in their life cycle?
- notochord –> longitudinal endoskeletal rod that gives strength and elasticity to the body
- dorsal hollow nerve cord –> a longitudinal, fluid filled nerve cord that runs along the back of the body (dorsally) just about the notochord
- pharyngeal slits —> lateral openings in the foregut (pharynx) of chordates, they were originally used for alter feeding
- Post anal tail –> muscular tail that extends past the anal opening
How do the lancets eat (branchistoma sp.)
- a suspension feeder
- burrows into sediment to feed using v-shaped muscle segments called myomeres
- anterior end they have a oral hood where they sort food particles, the cilia create a current that delivers food to the mucus lined pharynx
- water passes through pharyngeal slits into the atrium where it is dumped into the environment from the atripore
what part of the branchiostoma sp. shows segmentation?
their myomeres (have v-shaped muscle segments)
what features are required to filter feed?
- myomeres (to dig)
- oral hood (like mouth)
- cilia
- atrium
- atripore
what is one of the most distinctive characteristics of the vertebrate body? what is it composed of and what is the importance of it?
the endoskeleton which is composed of cartilage or bone
- it has allowed vertebrates to reach such large body sizes, use great variety of food sources and modes of locomotion
What are 2 types of vertebrate skeleton in bony fish? and what are they composed of?
Axial skeleton (skull and vertebrate):
- little specialization
- goes along the column from head to tail
- vertebral column of fish is divided into two regions: trunk and tail
Appendicular skeleton (girdles and appendages):
- jawed fishes have two fins: paired and unpaired
- unpaired fins are the dorsal, anal and caudal fins
- paired fins are the pectoral and pelvic fins and are associated with the pectoral and pelvic girdles
- pectoral girdle is against the base of the skull and pelvic girdle is maintained in position the pelvic area by muscle and connective tissue
What are 2 types of vertebrate skeleton in Tetrapods? and what are they composed of?
Axial skeleton (skull and vertebrate):
- more complex than fishes because they have to move without help of bouncy
- composed for 5 vertebral regions:
1. cervical vertebrae –> neck vertebrae responsible for moving head
2. thoracic vertebrae –> ribs area to protect heart and lungs and contribute to breathing
3. Lumbar vertebrae –> between rib cage and pelvic region used to strengthen the back
4. sacral vertebrae –> fused to the pelvic girdle and serve as muscle attachment
5. Caudal vertebrae –> tail vertebrae located behind the sacral region (reduced in humans)
Appendicular skeleton (girdles and appendages):
- homologous ones hared from a common “fish” ancestor that is present in all tetrapods
- pectoral girdle in tetrapods is not attached to the vertebral column, muscles and connective tissue maintain its position
- pelvic girdle is fused to the vertebral column in the sacral (pelvic) region.
Why does a pigeon have large breastbone associated with the thoracic vertebrae and ribs?
Because they use that area for flying (muscles) and it needs bigger bones for muscle attachement
Why is the human pelvic girdle so strong and robust? Why is the human spine not as flexible as the perch’s?
Because we have to support our big muscles like the thighs and to walk
- human spine is not as flexible because we only walk in one movement, and we don’t walk side to side
What adaptation to a bipedal upright lifestyle are evident in the human skeleton?
- legs are longer than arms
- “S” curved spine –> allows us to not fall forward and supports us
- our glutes help us walk and stand upright
How does the perch/fishes get their oxygen? even though there is more oxygen in the air than water why does a perch suffocate in air?
Fish don’t have lungs, they have gills. Water needs to pass through the gills so they can absorb the oxygen. they cannot take up oxygen in gas form because it cannot diffuse through their gills
