Nematocysts and Nematocytes

1. Nematocysts and Nematocytes

2. What the?

3. What is a Nematocyte? • All members of the phylum Cnidaria, which include corals, sea anemones, and jellyfish, have a common feature which is painfully obvious to anyone unfortunate enough to encounter one; nematocytes

4. What is a Nematocyte? • These are stinging cells, kind of… • secretory product of these cells, the nematocysts, actually do the stinging • Product from the golgi apparatus • Take less than 3 milliseconds to discharge

5. Why do Cnidarians have them? • No teeth, jaws, or hard tissues.. • Such animals require some means of capturing food without having the gelatinous tissue that they consist of destroyed by struggling prey. • Many of these nematocysts serve to immobilize prey with barbed spear like projections. Others types exist that entangle and hold onto intended prey by wrapping around them or sticking to them (colloblasts).

6. What do they look like, what is their structure?

7. What causes that sting? • Aside from having a spear in your body, • There are poisons in some types of nematocysts • The type of poison injected also depends on the type of prey being sought. • Fast acting toxins that cause cells membranes to rupture • Disruptive toxins that affect the action of nerve and muscle cell membranes and impair normal function, causing paralysis • Nematocyst can also have toxins which degrade collagen, break down proteins and lipids, and disrupt cellular influx of ions

8. How do they ‘fire’ • Tactile and chemical means • Both an outer trigger and chemical signals • Tactile cue is usually enough • Chemicals that help trigger discharge are found in prey species, why? • Source of power for that 3/1000 of a second discharge? Osmosis