1. Introduction to Marine Invertebrates
Ref: Lesson 18
Introduction to Marine Invertebrates

2. Kingdom Animalia 97% of animals on Earth are invertebrates
Except for insects, most are marine
Exception is Phylum Chordata which contains both.

3. 97% of animal species on Earth are invertebrates
97% of animal species on Earth are invertebrates. On Earth today, insects are the most numerous invertebrates. Many vertebrates are described as "fish", encompassing a large group of disparate classes or subphyla.

4. Structure and Function of Feeding in Invertebrates
Found nearly everywhere in the ocean
Majority speak their juvenile stages in the plankton community

5. Structure and Function of Feeding in Invertebrates
As adults – attach to substrates
Seafloor
Inside self-created shells/skeletons
Floating among plankton
Crawling on seafloor
Swimming within water column

6. Coral

7. Adult: much larger than juveniles
Figure 1: One example of a complex life cycle in a marine invertebrate. In this case, a benthic adult brittlestar releases its gametes into the water column where fertilization occurs and development takes place over a period of days to weeks. During this period a planktonic larval stage develops which is morphologically dissimilar from the adult. Eventually the larva settles as a benthic juvenile and the cycle repeats itself in the next generation. This pattern is common among marine invertebrates and the size of the egg is positively correlated with parental investment and predicts the length of the developmental period. Note that the images are not to scale. The adult is many times larger than the egg, larval and juvenile stages
Adult: much larger than juveniles

8. Niches
Multiple body forms allow for invertebrates to take on many “jobs” in their ecosystem
Each species occupies a different niche
Ex: 2 species of fish might eat the same smaller fish species, but one hunts at night while the other hunts during the day

9. Ex: Barnacles

10. Morphology
Important characteristic of how the organism carries out its niche is its structure
In animals, it is termed anatomy
Study of processes within its anatomy is called physiology

11. Body Plans Asymmetry – animal lacks symmetry
Simplest animals
Radial - arranged around a central axis so that each part extends from the center
Tend to be sessile (immobile)
Bilateral – has identical halves
Best for mobile creatures

12. Evolution of Body Plans

13. Anatomy

14. Physiology of Starfish

15. Feeding Techniques 1) Filter feeding
Great deal of food suspended in water column
Plankton or remains of larger organisms

16. Feeding Techniques Many bivalves pump water through their bodies
Known as active filter feeders

17. Bivalves pump water through incurrent siphon
Bivalves have a characteristic muscular foot on bottom and siphon on top
Bivalves pump water through incurrent siphon
Feather-like gills are enlarged to gather oxygen and food
Covered in cilia which beat to maintain constant water flow
Cilia trap food and push towards digestive system
Mouth, stomach, intestine, and anus
Clams, common bivalve mollusks, look like simple organisms, but have complex organ systems. The structures you see in the diagram have different functions. For example, gills extract oxygen from the water, while the heart pumps blood carrying oxygen and other materials to the animal's other organs.

18. Active filter feeder - Clams
Wastes (CO2 & food) released through excurrent siphon
Active pumping allows animal to counteract buoyancy of plankton
Clams, common bivalve mollusks, look like simple organisms, but have complex organ systems. The structures you see in the diagram have different functions. For example, gills extract oxygen from the water, while the heart pumps blood carrying oxygen and other materials to the animal's other organs.

19. Geoduck Clam – “Gooey duck”
This large Geoduck Clam dug by divers near Discovery Bay of Washington State is often called a "gooyduck". It shows the large siphons that some bivalves have. Water is sucked in through the incurrent siphon, and then filtered by the gills before the water is expelled through the excurrent siphon

20. Suspension Feeding
Type of filter feeding in which organisms do not create their own water currents
Rely on movement of water to bring them food
Ex: Crinoids
Crinoids are also known as sea lilies. They look like flowers but are actually echinoderms. They use their feathery arms to suspension feed.

21. Suspension Feeders
Members of Phylum Echinodermata are suspension feeders
Lined with tube feet connected to animal’s water vascular system
Sticky tube feet capture food particles
Transfer food to mouth an digestive system

22. 3) Deposit Feeders
Feed on detritus – remains of decomposing plants and animals on seafloor
Sift through sediment for food particles
Ex: Sea Cucumber

23. 3) Deposit Feeders
Uses modified feet around its mouth to scoop sand in
Important to marine ecosystem to recycle nutrients
Sea cucumbers have a slimy, rubbery texture. Delicacy in Asian countries, where they feel they benefit one’s health to reduce blood pressure. Tasteles so often prepared with flavorful ingredients.

24. 3) Deposit Feeders Unique strategy for evading predators
When threatened, permanently eject all internal organs through mouth or anus
This is called evisceration
Distracts predator so sea cucumber can escape
Eventually organs grow back and its good as new

25. 4) Herbivory
Eat plants and algae (including seaweed, some of which are protists)
Ex: Sea Urchin
Will puncture your foot, some contain toxins

26. Sea Urchins
Coordinate tube feet and spines to move slowly along seafloor and rocks
Specialized organ called Aristotle’s Lantern – resembles ancient Greek lantern
Urchin pushes 5 teeth through its mouth
Scrapes pieces of kelp or algae

27. Aristotle’s Lantern
The broken sea urchin in this photograph allows us to get a view of Aristotle's Lantern, a sharp structure used to bite off pieces of algae. Notice the five teeth made up of calcium carbonate that make up the structure. Recall that one of the characteristics of echinoderms is their five-part radial symmetry.

29. Urchins are major part of Sea Otter’s diet
Urchins are major part of Sea Otter’s diet. Keeps the population in check

30. 5) Predation Many invertebrates feed on other animals
Predators that subsist almost solely on other animals are carnivores - Ex: Sandworm from Phylum Annelida - classic segmentation, crosswire rings

31. 5) Predation Polychaetes that have fleshy extensions called parapodia
bristles used for swimming or crawling
powerful hook-like jaws to grab their prey