5. First organism with specialized cells
Contain layers of specialized cells
Amoebocytes:
Move with in walls of sponge
and carry food to other cells.
These amoebocytes are considered as
precursors to Cardiac muscle cells or
myocardiocytes.
6.
7. First organism with muscular tissues.
Presence of muscles in oral cavity as
pump for one way flow of water.
Due to this the origins of the heart
pump are believed to have started
with the pumping of a jellyfish.
8.
9. First organism with
organs
No typical circulatory
system found
Breath through skin
10. Dorsal vessel (heart) muscular areas
for pumping.
Open circulatory system.
No blood vessels or very few.
Accessory heart:
In addition to the dorsal vessel
insects have accessory heart that
supply body appendages with
hemolymph.
11. No actual heart.
These muscular regions are
the precursors to our
complex human heart.
12.
13. first animals with a two-
chamber heart consisting
of a ventricle and an
atrium.
27. 1. Formation of septum between
atria(amphibians).
2. Formation of septum between
ventricle(crocodiles)
3. Disappearance of the sinus
venosus and the conus
arteriosus (birds and
mammals).