More about cartilaginous fish

Cartilaginous and bony fish regulate the salt found in water by:
Fish- drink a lot of seawater for hydration and excrete the concentrated salt through their gills and gut
Sharks- Reabsorb the area by the breakdown of protien back into their tissue

Sharks have developed a life strategy that requires slow growth to a relatively large size, while fish demonstrate rapid growth and reach maturity faster

Shark reproduction is internal. They have pelvic claspers that serve as the sperm conducting structure for internal fertilization.

What are cartilaginous fish

Cartilaginous fish differ from other fish because they have skeletons made of cartilage

Examples of cartilaginous fish include sharks, rays, and chimeras

A sharks eye is special because some can protect their eye with a tough 3rd eyelid, and some even have a muscle that can roll their eye backward for protection.

Differences between bony and cartilaginous fish:

Sharks have fewer and larger blood cells

Shark skin is covered by dermal denticles and bony fish are covered in flat scales

Shark kidneys and genitals empty in only one opening while bony fish have two separate openings, the rectum and the anus.

Marine Science Words of Wisdom

"Dont wander away unseen for ten years...come back and visit often" Sea turtle hatchlings have to make their way from their nest on shore to the open ocean, alone. From the time they take their first swim until they return to the coastal ocean to forage as juveniles can take up to a decade and is called “the lost years” because they are so hard to track.

Nine Major Animal Phyla

The nine major phyla are:


1. Phylum Porifera - The Sponges
2. Phylum Coelenterata – The Coelenterates: jellyfish, hydras, corals

3. Phylum Platyhelminthes – The Flatworms: planaria, tapeworms

4. Phylum Nematoda – The Roundworms

5. Phylum Annelida – The Segmented Worms: earthworm, leech, sandworm

6. Phylum Arthropoda – The Arthropods: insects, spiders, crustaceans

7. Phylum Mollusca – The Mollusks: clams, snails, oysters, octopus

8. Phylum Echinodermata – The Echinoderms: sea stars, sea urchins

9. Phylum Chordata – The Chordates: fish, reptiles, amphibians, birds, mammals

• The types of habitats they can be found in are salt water, fresh water, and terrestrial.

• Some species dont have digestive systems, but those who do either have a complete or incomplete one.
• I have seen birds in the shy flying by as an example of a species in a phyla